DE102016224569A1 - Power control device for an electrical machine and method for separating an electric machine from an electrical energy storage - Google Patents

Abstract

A power driving apparatus for an electric machine will be described. An inverter (IN) is connected between a DC voltage terminal (GA) and an AC voltage terminal (WA) of the electric machine (EM). A controller (C, C1) is followed by a semiconductor bridge circuit (11-23; H1-H24) of the inverter (IN). The bridge circuit (11-23; H1, H11, H21) has a first semiconductor switch (11-13; H1, H11, H21) interposed between the AC voltage terminal (WA) and a first potential of the DC terminal (GA). A second semiconductor switch (S1; H3, H13, H23) of the power driver (LS) is antiserially connected to the at least one first semiconductor switch (11-13; H1-H21) and to the first potential (P; EA1) of the DC terminal. The controller (C; C1, C2) has a separation signal input (FE). The controller (C; C1, C2) opens the first and the second semiconductor switch when a disconnect signal occurs. A method for disconnecting an electric machine (EM) from an electrical energy store (ES) is also described, in which a disconnect signal is applied First and one (this antiparallel connected) second semiconductor switch (11-13, H1, H11, H21) is opened.

Description

It is known to equip a vehicle with an electric drive, wherein an electrical energy store in the form of a rechargeable battery supplies the energy for operating the electric drive. To drive a vehicle relatively high power levels are required, so that the drive must be designed according to this power. In order to reduce the conductor diameter and the current to be controlled with the same (high) power, relatively high operating voltages for electric drives and their energy storage are used. For example, voltage levels of more than 300 volts may occur here, in particular more than 350 volts, for example 400 volts or even 600 volts or 800 volts.

Since these high voltages pose a high safety risk, care must be taken that the contact voltage is harmless, for example during maintenance or in the case of an accident. To achieve this, contactors are usually used, that is, electromechanical switches, which separate the energy storage from the rest of the vehicle electrical system.

Such electromechanical switches must be designed for high holding currents (corresponding to the maximum traction power) and, in particular, for high switching powers in order to switch reliably in order to interrupt the flow of current. This is associated with high costs, even if the switching events are rare and limited to maintenance or accident.

It is an object of the invention to show a possibility with which, in particular, the cost of implementing a reliable separation process can be reduced.

This object is achieved by the power drive device and by the method according to the independent claims. Further embodiments, features, properties and advantages will become apparent from the description and the attached figures.

It is proposed to use for the separation of the electrical energy storage semiconductor switches, which already perform functions of an inverter and / or a DC-DC converter. As a result, at least one potential of the energy store can be disconnected without the need for an electromechanical disconnecting switch (for separating this potential). It can be saved at least one of the two circuit breakers (one disconnector per potential of the energy storage). In order to prevent a current flow in both directions (with respect to the energy storage), two semiconductor switches are opened, which are arranged antiserially to each other when an error signal is present. Both semiconductor switches are part of an inverter or part of an inverter and a DC-DC converter. The two semiconductor switches (i.e., the first and second semiconductor switches) antiserially (directly or indirectly) between an AC terminal and a DC terminal of the power control device. In a current path leading from the AC terminal to the DC terminal, the two semiconductor switches (i.e., the first and second semiconductor switches) are sequentially switched and antiseries to each other. In other words, the operating directions of the first and second semiconductor switches, in which they are controllable by external signals, are opposite to one another, the working directions being viewed in a current path leading from the AC connection to the DC connection.

Both (ie the at least one first and the at least one second) of the anti-serially connected semiconductor switch may be part of the bridge circuit of an inverter, or one of these two semiconductor switches (namely the at least one first semiconductor switch) may be part of the bridge circuit of the inverter, and at least one other semiconductor switch (namely, the second) may be part of a DC-DC converter. Such a DC-DC converter can be connected approximately between the energy store and the inverter, for example to bring the operating voltage of the inverter to a desired level or to keep constant.

A power driving apparatus for an electric machine will be described. In particular, this relates to a power control device in a vehicle electrical system. The electric machine may be an electric machine of a traction drive, a starter generator or other component, such as an electric air conditioning compressor. The power drive device has a DC voltage terminal and an inverter. The inverter is provided between the DC voltage terminal and an AC terminal of the power driving device. The AC voltage connection is intended for connection of the electrical machine. The power driving device is provided for an electric machine such that the power driving device has an inverter capable of outputting (or also picking up) three-phase current at the AC power terminal. The inverter has a semiconductor bridge circuit. The inverter is unidirectional or bidirectional and is in particular arranged, from DC voltage, at the DC voltage connection or at a DC voltage side of the inverter is applied to generate an AC voltage, in particular a three-phase current, at the AC voltage terminal. For this purpose, the individual semiconductor switches of the semiconductor bridge circuit are selectively controlled in a known manner.

The power drive device includes at least one controller. This is drivingly connected to the semiconductor bridge circuit, in particular with their semiconductor switches. The controller has a disconnect signal input to which a disconnect signal may be received, the controller configured to open the at least one first and the at least one second semiconductor switch upon receiving a disconnect signal. The controller (or other controller), along with the semiconductor bridge circuit, is configured to convert a DC voltage at the DC voltage terminal into a three-phase current for delivery to the AC voltage terminal. The inverter can be connected directly to the DC voltage connection, that is to say without the change in the voltage level, or the inverter can be connected to the DC voltage connection indirectly, in particular via a DC-DC converter. The controller is preferably configured to drive the semiconductor bridge circuit to convert a DC voltage at the DC voltage terminal into a three-phase current for delivery to the AC voltage terminal. However, this function can also be implemented in another controller, which is preferably connected to the controller for opening semiconductor switches when a disconnect signal occurs, or via a common control unit (control unit).

The semiconductor bridge circuit has at least one first semiconductor switch, which is connected between the AC voltage terminal and a first potential of the DC voltage terminal. In other words, the at least one first semiconductor switch is connected between the AC voltage terminal and a potential rail having the first potential. At least one second semiconductor switch of the power drive device is connected in antiseries to the at least one first semiconductor switch. The first and the second semiconductor switches are connected in parallel succession between the DC voltage connection and the AC voltage connection (directly or indirectly via a further component, for example via an inductance). The at least one second semiconductor switch is connected to the first potential (that is, to a first potential rail) of the DC voltage terminal. The at least one first and the at least one second semiconductor switch are provided in series between the DC voltage terminal and the AC voltage terminal.

The controller has a disconnect signal input. This is set up to receive a disconnect signal. The isolation signal corresponds to an error signal representing an error requiring the disconnection of the electric machine. The controller is configured to open the at least one first semiconductor switch and the at least one second semiconductor switch when the isolation signal occurs. The separation signal can be reproduced, for example, by a certain level or by a specific signal sequence. The controller may be composed of one or more individual controls, each controller having such a separator signal input. In particular, if the at least one first semiconductor switch is provided in a different bridge circuit or on a different component than the at least one second semiconductor switch, then a plurality of control elements may be present (preferably one per component), which each have a corresponding isolating signal input. In addition, a higher-level control unit may be provided, to which the control or the control units are or are arranged downstream.

A first possibility is that the at least one first semiconductor switch and the at least one second semiconductor switch are provided in the same component (and in particular are set up to realize a function together). Therefore, the at least one first semiconductor switch and the at least one second semiconductor switch may be part of the semiconductor bridge circuit or each part of the inverter. The semiconductor bridge circuit therefore has at least two semiconductor switches, which are connected in antiseries to one another between the AC voltage connection and the DC voltage connection. The semiconductor switches are in particular switchable by external signals. The semiconductor switches are in particular configured to control (in particular to switch) current in a flow direction in accordance with a signal at a control input. Furthermore, the semiconductor switch may not be able to control the current flow in accordance with an external control signal in an opposite current flow direction, in particular if the semiconductor switch has inverse diodes or body diodes which bridge the relevant switching element counter to the direction of flow (in controllable operation). This is the case, for example, with field-effect transistors such as MOSFETs and IGBTs. As a semiconductor switch of the power drive device mentioned here (and the method mentioned here) are thus preferably field effect transistors such as MOSFETs or IGBTs. In order to prevent a current flow in both directions, it is provided that at least one first and at least one second semiconductor switch is provided, which are connected in series, However, in their working direction (in which a control of the flow of current by means of external signals is possible) are opposite to each other. In other words, the direction of the source-drain or the direction of the collector-emitter of the first and the second semiconductor switch may be opposite to each other. Such an antiserial series circuit relates to the view of a current flow between AC voltage terminal and DC voltage terminal.

The semiconductor bridge circuit is in particular an H-bridge circuit. The at least one first semiconductor switch and the at least one second semiconductor switch are part of this H-bridge circuit. In this way, only one control can be provided, namely that which controls the semiconductor switches of the H-bridge circuit, and which further comprises a separation signal input as described herein. As a result, the at least one first and the at least one second semiconductor switch receive a further function, namely the function of disconnecting the electrical machine from the energy store or from the DC voltage connection, in addition to the usual function of the inverter, from the DC voltage at the DC voltage connection to a three-phase current at the AC voltage connection produce.

An H-bridge circuit comprises two series circuits or branches for each phase of the AC voltage connection. Each series circuit comprises two semiconductor switches connected in series with one another, which extend in particular between the two supply potentials of the DC voltage connection (for example ground and a positive supply potential). The at least one first semiconductor switch and the at least one second semiconductor switch belong to the same phase and in this case are assigned to different series circuits (of the same phase). The first and the second semiconductor switch are connected to the same supply potential, in particular to the positive supply potential of the inverter.

The AC voltage terminal has a plurality of phases, each phase being connected to a connection point between two series-connected semiconductor switches. The H-bridge circuit comprises a full-bridge circuit for each phase, the bridge between the two branches (which are each provided by two series-connected semiconductor switches) each formed by an inductance. One of the two branches is connected to the DC voltage connection (directly or indirectly via a DC-DC converter), while the other series connection of the same phase is connected to one phase of the AC voltage connection (or the electrical machine). In particular, the first and the second semiconductor switch are connected in series here for one phase, for several phases or for all phases, in particular via the inductor or via the bridge, which connects the two branches of the H bridge circuit.

Another possibility is that the at least one first semiconductor switch is part of the inverter or the semiconductor bridge circuit, and the at least one second semiconductor switch of another component (and in particular another function) belongs, and for example part of a DC-DC converter. Therefore, the power drive device may comprise a further component, in particular in the form of a DC-DC converter, wherein this component is connected in series between the DC voltage input (for connection of the energy storage device) and the inverter. The DC-DC converter or this component has semiconductor switches, of which at least one forms the second semiconductor switch. In other words, the at least one second semiconductor switch is part of the DC-DC converter or this component. The first semiconductor switch is part of the semiconductor bridge circuit or part of the inverter. The DC-DC converter is in particular a synchronous converter with two series-connected semiconductor switches. The ends of the series circuit formed in this way are connected to the inverter or to its DC side.

The DC-DC converter also has an energy store, for example in the form of an inductance or a capacitor. In particular, an inductance of the DC-DC converter between the first potential or the DC voltage terminal of the power drive device and the node of the two semiconductor switches may be connected, which are connected in series as mentioned. There may be provided a controller which drives both the component or the DC-DC converter and the inverter, and further comprising a separation signal input. Such a controller is set up to open both at least one first and the at least one second semiconductor switch when a disconnect signal or an error signal is received. Furthermore, a first control can be provided, which drives the semiconductor switches or the bridge circuit of the inverter, and a second control can be provided, which drives the semiconductor switches of the DC-DC converter or the component. Both controllers preferably each have a separation signal input. Both controllers are set up to open the respective semiconductor switches upon receipt of a disconnect signal or an error signal. The first component is set up to open at least a first semiconductor switch when a disconnect signal is received. The second controller is configured to open the at least one second semiconductor switch when a disconnect signal is received.

Finally, a higher-level control unit may be provided, as well as a first and a second controller, wherein the first controller controls the semiconductor switches of the component or the DC-DC converter and the second controller controls the semiconductor switches of the inverter or its bridge circuit. The first and the second controller are connected downstream of the higher-level control unit. The higher-level control unit can have a separation signal input. The higher-level controller is drivingly connected to the first and the second controller. The first and the second controller and the higher-order control unit are set up to receive the at least one first semiconductor switch and the at least one second semiconductor switch upon receipt of an error signal or separation signal (in particular at the isolating signal input of the higher-order control unit).

The semiconductor bridge circuit (of the inverter) may be a fully controlled three-phase bridge circuit. In this case, it is provided for each phase that two semiconductor switches are connected in series and are connected to the DC voltage connection. The AC voltage terminals correspond to the connection points between the semiconductor switches. In particular, the semiconductor bridge circuit is a B6C pressure or generally a BnC bridge, where n represents the number of phases multiplied by two. The capital letter C in this abbreviation again states that the switching elements of the bridge circuit can be controlled by external signals. Again, the semiconductor switches are preferably field effect transistors such as MOSFETs or IGBTs. The at least one first semiconductor switch is connected between the DC-DC converter and the AC voltage connection. The at least one first semiconductor switch is thus a switch of the series connection of two switches, which constitutes a branch or a phase of the full-bridge circuit. The at least one second semiconductor switch is a part of the DC-DC converter or a component which is connected between the semiconductor bridge circuit of the inverter and the DC voltage connection. In particular, the at least one second semiconductor switch is connected to the first potential via the memory element (of the DC-DC converter which forms the component). The memory element is in particular an inductance, via which the semiconductor switches of the DC-DC converter are connected to the first potential.

The first potential is in particular the positive potential of the energy store (which feeds the inverter). In particular, the mass can be used as the second potential of the DC voltage connection. It may be provided that there is an interruption between an electromechanical or other element between the ground connection of the energy store and the inverter (in particular between the energy store connection and the DC-DC converter, if present). It can be provided that at least one of the controls or the higher-level control unit opens this disconnect switch in the second potential (the ground terminal of the energy store downstream) upon receipt of a corresponding disconnect signal or error signal, preferably simultaneously with the opening of the first and second semiconductor elements. The energy store is preferably a high-voltage energy store with an operating voltage of more than 60 volts, in particular more than 120 volts and preferably more than 300 or 360 volts. For example, the operating voltage of the energy storage 400 volts, 600 volts or even 800 volts. The energy store is, for example, a lithium-based battery with several series-connected galvanic cells (based on lithium technology). The energy storage is in particular a traction storage of the vehicle electrical system.

The controller, the controllers or the higher-order control unit can furthermore be designed to permanently open the at least one first and the at least one second semiconductor switch, in particular until a reset signal is present. Further, these control elements of the power drive device may be configured to drive the at least one first and the at least one second semiconductor switch with an open state after a disconnect signal has occurred, in particular until a reset signal is received. The error or disconnect signal may be provided by a body controller or by a safety device configured to detect a maintenance condition and / or configured to detect an accident or imminent accident. It can be provided (or more) control, which drives the semiconductor switch of the inverter for converting AC voltage into DC voltage and / or the semiconductor switch of the DC-DC converter for converting DC voltage into DC voltage (other height). At least one further control may be provided, which activates the at least one first and / or the at least one second semiconductor switch for opening when a disconnection signal has been received. However, it can also be provided that the at least one controller, which controls the function of the conversion, also opens the first and / or second semiconductor switch, if one Isolation signal is received. While the semiconductor switches to be opened upon receipt of a disconnect signal are part of the inverter and possibly also part of a DC-DC converter, it may be provided that the respective controllers are separated with respect to these functions (converting and disconnecting).

As mentioned, the at least one first semiconductor switch and the at least one second semiconductor switch are transistors which have a body diode or inverse diode. This is due in particular to field effect transistors by the structure of the semiconductor switch. It may further be provided that a diode is connected as a discrete component antiparallel to a semiconductor switch. In this case, as well as in the case of inverse diodes, it is possible for current to flow in the opposite direction to the working direction or the usual forward direction of the semiconductor switch, in particular independently of an external triggering. In order to prevent current from flowing counter to the working direction, the first and the second semiconductor switches are connected in antiseries to one another (viewed from the DC connection in the direction of the AC connection).

Furthermore, a method for separating an electric machine from an electrical energy store is described. First, a separation signal is detected. When detected, at least one first semiconductor switch and at least one second semiconductor switch are opened. These are antiparallel to each other. The semiconductor switches are provided between the electrical machine or its AC connection and a DC voltage connection, in particular a first potential of the DC voltage connection. As mentioned, the DC voltage terminal and the AC voltage terminal are preferably terminals of a power driving device provided between the power storage and the electric machine for controlling the power supply from the battery to the electric machine. The at least one first semiconductor switch is part of an inverter which is connected between the electrical energy store (or the DC voltage connection) and the electrical machine (or the AC voltage connection). Likewise, the at least one second semiconductor may also be part of an inverter. Alternatively, the second semiconductor switch is part of another component which is provided between the energy store and the electrical machine, in particular a DC-DC converter. The method preferably uses the components of the power drive device.

When opening the first and the second semiconductor switch, preferably two semiconductor switches are opened, which are part of a semiconductor bridge circuit of the inverter. The opening of the first and second semiconductor switches is therefore implemented by opening at least a first and at least one second semiconductor switch of the semiconductor bridge circuit of the inverter. In this case, the at least one first and the at least one second semiconductor switch are part of the inverter. In other words, as a first and second semiconductor switch two mutually antiparallel semiconductor switches are opened, which are part of the inverter. The inverter in this case comprises in particular an H-bridge. Further, the first and second semiconductor switches are connected to the same (DC) potential.

Alternatively, the opening of the at least one first semiconductor switch may include: opening at least one semiconductor switch which is part of a semiconductor bridge circuit of the inverter. In this regard, this corresponds to the method mentioned above. The opening of the at least one second semiconductor switch, however, comprises opening at least one semiconductor switch which is part of a DC-DC converter. The DC-DC converter is in this case connected between the energy storage and the inverter. In other words, a semiconductor switch of the inverter is opened as the first semiconductor switch, and as a second semiconductor switch is a semiconductor switch of the DC-DC converter. The signs of the supply potentials to which the first and second semiconductor switches are connected are identical. Preferably, all of the semiconductor switches of the inverter are opened as (multiple) first semiconductor switches connected to the same supply potential (i.e., to a supply potential of the same sign as the supply potential to which the second semiconductor switch is connected).

During the operation of the DC-DC converter for the conversion of DC voltage that semiconductor switch is repeatedly opened and closed, which is opened (permanently) even when the separation signal.

The opening of the respective semiconductor switch after receiving or due to the separation signal relates to an opening phase which is significantly longer than the opening phase of a semiconductor switch during operation of the DC-DC converter. In particular, after receiving a disconnection signal, the open state of the at least one first and the at least one second semiconductor switch lasts until a reset signal is present.

The 1 and 2 show vehicle electrical systems with a power drive and serve to explain the described here Approach and the Leistungsansteuervorrichtung described here.

The 1 exemplifies a vehicle electrical system in which a power drive LS connects an electrical energy storage ES, in particular an accumulator, with an electric machine EM. In order to generate an alternating current from the DC voltage of the energy store ES, the power drive device LS comprises an inverter IN with a semiconductor bridge circuit provided by the switches 11 . 12 . 13 . 21 . 22 and 23 is formed. The bridge circuit of the inverter IN is a B6C bridge, wherein a branch is provided for each phase, which comprises two semiconductors connected in series. A first branch relating to a first phase of the electric machine is formed by the semiconductor switches 11 and 21 , another branch (concerning a second phase) is formed by the semiconductor switches 12 and 22 , and a third branch (concerning a third phase) is formed by the semiconductor switches 13 and 23 , Thus, the in 1 illustrated embodiment, three-phase, but the number of phases is not limited to this number. In particular, six phases can also be used.

In each branch there is a connection point A1, A2, A3, at which the semiconductor switches of a branch are connected to each other. The serially connected semiconductor switches of each branch are connected to a positive and a negative supply potential of the inverter IN. The connection points A1 - A3 are led to an AC voltage connection WA and correspond to the phase connections of the electrical machine.

A DC-DC converter DCDC, shown here as a synchronous converter, comprises a series connection of two semiconductor switches S1 and S2. The ends of this series circuit are connected to the inverter IN. Via an inductance IND, the connection point between the two switches S1 and S2 is connected to a first potential P of the energy store ES. The DC-DC converter DCDC and the inverter IN are further connected to ground M, wherein this also corresponds to the mass of the energy store, and may also be referred to as a second potential.

Via an AC voltage terminal WA, the power drive device LS is connected to the electric machine EM. The inverter is connected either directly to the first potential P or, as shown, via the optional DC-DC converter DCDC to the energy store ES.

In the illustrated embodiment, a controller C1, which may be part of or may be external to the inverter, part of the power driver, controls the semiconductor switches 11 to 23 of the inverter IN to generate a three-phase current from the DC voltage applied to the inverter in normal operation at the AC output WA. By means of this three-phase current, a magnetic rotating field is generated in the electric machine. The inverter can also be bidirectional and be configured to convert an AC voltage, which is applied to the AC voltage terminal WA, into a DC voltage for feeding the energy store ES.

Another controller C2 controls the switches S1, S2 of the DC-DC converter DCDC. The controller C2 is set up to control the switches for converting a DC voltage (into another DC voltage).

Both controllers C1 and C2 each have a separation signal input FE1, FE1 ', at which a separation signal or an error signal can be detected. The controls C1 and C2 are arranged to open switches upon receipt of such a disconnect signal. In the case of the controller C1, this is at least the switch 11 , but also the switches 12 and 13 and thus all switches can be opened, which are between the AC terminal WA and the supply potential of the inverter (corresponding to the positive output of the DC-DC converter).

The controller C2 of the DC-DC converter DCDC is configured to open the switch S1 upon receipt of the disconnect signal. Starting from the AC voltage terminal WA and a current path to the first potential P following are the switch 11 and the switch S1 (of the DC-DC converter DCD) are connected in antiserial to each other, so that despite their inverse diodes (for example, the inverse diode 1 of the switch 11 ) in any direction a current can flow. This results in a complete separation between the DC voltage connection GA (to which the energy store ES is connected to the power control device ELS) and the AC voltage connection WA. The two anti-serially connected switches in the case of separation belong according to the example of 1 different components of the power drive device, namely the inverter IN and the DC-DC converter DCDC. Both anti-serially connected switches are connected to the same supply potential, namely to the positive supply potential of the inverter (corresponding to the positive output potential of the DC-DC converter DCDC). The first and second semiconductor switches are in this case directly connected to each other (but with opposite directions of operation).

The controls C1 and C2 are arranged in the illustrated embodiment to open upon receiving such a separation signal, the semiconductor switches. It can be provided that at least one control is used for the function of the conversion for the inverter IN and the DC-DC converter DCDC, while at least one second control is used for the function of opening the first and second semiconductor switches (which includes a separation signal input FE and possibly also a separation signal input FE ').

In the 2 another vehicle electrical system is exemplified, which serves to further explain the procedure described.

Here, too, an energy store ES is connected to an electric machine EM via the power drive device. Here, the power drive LS has a DC voltage terminal GA, to which the energy store is connected, and an AC voltage terminal WA, to which the electric machine EM is connected. Again, the electric machine EM and the AC voltage terminal WA of the Leistungsansteuervorrichtung LS are multi-phase. An (optional) DC-DC converter DCDC may be provided, which is connected between the DC voltage terminal GA and the inverter IN of the power driver LS, or it may be provided no DC-DC converter DCDC, which realized differently depending on the operating voltages used of the energy storage and the electric machine can be.

The inverter IS comprises a multi-phase H bridge circuit. Each phase of the H bridge circuit of the inverter IN comprises two branches, each comprising two series-connected semiconductor switches. In each phase of the H-bridge circuit, a branch or series connection of two semiconductor switches is connected to a DC potential EA1, EA2 of the inverter (which may correspond to the terminals of the energy store). In other words, in each phase of the H bridge circuit, a branch of a pair of semiconductor switches is connected to a DC side of the inverter IN and to a DC terminal of the inverter, respectively.

In each phase, a second branch or a second series connection of two semiconductor switches is connected to the AC voltage terminal WA. The first branches or the first series circuits, which are connected to DC potential GA1, GA2 or to the energy store ES, are the semiconductor switches H1, H2 for the first phase, H11, H12 for the second phase and H21, H22 for the third phase , The series circuits of two semiconductor switches thus shown on the left side can be regarded as the DC side of the inverter, while the other branches or series circuits (H3, H4, H13, H14, H23, H24) can be considered as the AC side.

Parallel to the branches of the AC side of the inverter, capacitors C21, C22 and C23 are connected in parallel. As a bridge element between the branches of each phase in each case an inductance L1, L2 and L3 is connected in series. Relative to the electrical machine, the multi-phase H bridge circuit is thus connected in series between the DC voltage connection GA and the AC voltage connection WA.

A controller C, which may be part of the power drive device, is set up to drive the semiconductor switches H1 to H24 in normal operation in order to convert the DC voltage at the DC voltage terminal GA or at the supply potentials EA1, EA2 into an AC voltage at the AC voltage terminal WA. Optionally, the power drive device is also configured bidirectionally, so that the controller C can be configured to convert an AC voltage at the AC voltage terminal WA into a DC voltage at the DC voltage terminal GA.

The controller C comprises a separation signal input SE, at which a separation signal can be received. The controller C is set up to open the switches, which are located between the phase terminals of the AC voltage terminal WA and the DC voltage terminal GA at the occurrence of an error signal or separation signal at the input SE. For the upper phase these are the switches H1 and H3, for the middle phase they are the switches H11 and H13 and for the lower phase they are the switches H21 and H23. In the illustrated embodiment, those switches which are opened at a disconnect signal, the switches which are connected to the first potential of the energy store ES, in the illustrated case, the potential EA1, which may correspond to a positive pole. There are also complementary embodiments conceivable. Starting from the AC voltage connection WA to the DC voltage terminal GA leader in each phase, the switches open by the controller C are anti-parallel to each other. This results in a complete separation between the AC voltage terminal WA and the DC voltage terminal GA.

Alternatively, a controller C may be provided with a disconnect signal input FE as shown, which implements the step of opening, while another controller drives the semiconductor switches of the inverter in normal operation to produce a three-phase current.

As well as in 1 applies to 2 or for other embodiments, that the control for opening the semiconductor switch in the presence of a separation signal has priority, if this control does not correspond to the control that drives the semiconductor switches for normal operation (= conversion of voltage).

It should be noted that also in the 1 at least one switch is opened when a disconnect signal occurs (such as a switch 11 or the switches 11 . 12 and 13 ), which are between the AC voltage terminal and the first potential P, which in the 1 can correspond to the positive supply potential.

In the illustrated examples of 1 and 2 Further, an additional circuit breaker may be provided in the ground path, which is (directly) connected downstream of the energy storage, and which is also opened upon the occurrence of an error signal or separation signal.

As mentioned, the opening of the switches (also of the further switch) is permanent and in particular continues until a reset signal, in particular from the controller C, C1 and C2, has been detected. While in the 1 Preferably, both at least one switch of the inverter and a switch of the DC-DC converter DCDC are opened when an error signal occurs, in order to provide two mutually antiserial switches in the open state, it is in the embodiment of 2 possible that two switches of the inverter itself be opened, in the case of 2 the switches H1 and H3, as well as the switches H11 and H13 and also the switches H21 and H23. The mutually antiserial switches, which are opened in the case of a disconnect signal, are connected in series to semiconductor switches, which are connected directly to ground or with a potential which does not correspond to the first potential.

For both figures and also for other embodiments: A power drive device for an electric machine is described. An inverter IN of the device is connected between a DC voltage terminal GA of the device and an AC voltage terminal WA for the electric machine EM. The power drive device has a control, which is connected downstream of a semiconductor bridge circuit of the inverter IN. The semiconductor bridge circuit has at least one first semiconductor switch which lies between the AC voltage connection and a first potential of the DC voltage connection. A second semiconductor switch of the power drive device is antiserial to the at least one first semiconductor switch and connected to the first potential of the DC voltage terminal. The controller has a disconnect signal input for receiving a disconnect signal. The controller opens the at least one first and the at least one second semiconductor switch when a disconnect signal occurs.

Furthermore, a method for separating an electric machine EM from an electrical energy store ES is described, in which, upon detection of a disconnection signal, at least one first and at least one second semiconductor switch (connected in antiparallel) is opened. The semiconductor switches are connected between the electric machine EM and a first potential of a DC voltage terminal GA. The semiconductor switches are part of an inverter and optionally also a DC-DC converter DCDC between inverter IN and energy storage ES.

Claims (10)

Power control device (LS) for an electric machine (EM) with a DC voltage connection (GA) and an inverter (IN), which is connected between the DC voltage connection (GA) and an AC voltage connection (WA) for connection of the electric machine (EM) and the one Semiconductor bridge circuit (11-23; H1-H24), the power driving device comprising a controller (C, C1) drivingly connected to the semiconductor bridge circuit (11-23; H1-H24), wherein the semiconductor bridge circuit (11-23; H1, H11, H21) comprises at least one first semiconductor switch (11-13; H1, H11, H21) connected between the AC voltage terminal (WA) and a first potential (P; EA1) of the DC voltage terminal (GA), and the power driver (LS) further comprises at least one second semiconductor switch (S1; H3, H13, H23) antiserially connected to the at least one first semiconductor switch (11-13; H1-H21) and at the first potential (P; EA1) of the DC voltage terminal is connected, wherein the controller (C; C1, C2) further comprises a disconnect signal input (FE) adapted to receive a disconnect signal, and the controller (C; C1, C2) is arranged to open the at least one first semiconductor switch and the at least one second semiconductor switch, if any Isolation signal occurs. Power drive device according to Claim 1 , wherein the at least one first semiconductor switch (H1, H11, H21) and the at least one second Semiconductor switches (H3, H13, H23) are part of the semiconductor bridge circuit (H1 - H24). Power drive device according to Claim 2 wherein the semiconductor bridge circuit (H1 - H24) is an H-bridge circuit and the at least one first semiconductor switch (H1, H11, H21) and the at least one second semiconductor switch (H3, H13, H23) are part of the H-bridge circuit. Power drive device according to Claim 3 wherein the H-bridge circuit for each phase (PA1 - PA3) of the AC voltage terminal in each case two series circuits each with two series-connected semiconductor switches (H1, H2; H3, H4; H11, H12; H13, H14; H21, H22; H23, H24) wherein the at least one first semiconductor switch (H1, H11, H21) and the at least one second semiconductor switch (H3, H13, H23) belong to the same phase and different series circuits. Power drive device according to Claim 1 , which further comprises a DC-DC converter (DCDC), via which the DC voltage connection (GA) is connected to the inverter (IN) and wherein the at least one first semiconductor switch (H11) is part of the semiconductor bridge circuit and the at least one second semiconductor switch (S1) Part of the DC-DC converter (DCDC) is. Power drive device according to Claim 5 , wherein the DC-DC converter (DCDC) comprises a memory element (IND) and at least one semiconductor switch (S1) connected between the memory element (IND) and the inverter (IN), said at least one semiconductor switch (S1) the at least one second semiconductor switch forms. Power drive device according to Claim 5 or 6 , wherein the semiconductor bridge circuit is a fully controlled three-phase bridge circuit and the at least one first semiconductor switch (11) between the DC-DC converter (DCDC) and the AC voltage terminal (WA) is connected, wherein the at least one second semiconductor switch (S1) via the memory element (IND) with the first potential (P) is connected. Method for separating an electric machine (EM) from an electrical energy store (ES), comprising: Detecting a separation signal; and Opening at least one first semiconductor switch (11-13; H1, H11, H21) and at least one second semiconductor switch (S1; H3, H13, H23) connected in anti-parallel with the first semiconductor switch, the semiconductor switches being connected between the electrical machine (EM) and a first potential (P, EA1) of a DC voltage terminal (GA), wherein at least one of the first and second semiconductor switches is part of an inverter (IN) connected between the electrical energy store (ES) and the electric machine (EM). Method according to Claim 8 wherein the opening of the at least one first semiconductor switch comprises: opening at least one semiconductor switch (H1, H11, H21) which is part of a semiconductor bridge circuit of the inverter (IN), and opening the at least one second semiconductor switch comprises: opening at least one semiconductor switch (H3, H13, H23), which is also part of a semiconductor bridge circuit of the inverter. Method according to Claim 8 wherein opening the at least one first semiconductor switch comprises: opening at least one semiconductor switch which is part of a semiconductor bridge circuit of the inverter (IN) and opening the at least one second semiconductor switch comprises: opening at least one semiconductor switch forming part of a DC-DC converter (DCDC ), which is connected between the energy storage (ES) and the inverter (IN).

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