Method and device for operating an on-board network

Abstract

Method for operating an on-board network (BN) with - a three-phase motor (DM) having a stator and a rotor, the stator having a first at least three-phase winding (W1) and at least one second at least three-phase winding (W2) which are inductively coupled to one another, - a first and at least one second partial electrical on-board power system (TEB1, TEB2), - a first actuator (SG1) which is electrically connected to the first winding (W1) and the first electrical partial energy system (TEB1), - at least one second actuator (SG2) which is electrically connected to at least the second winding (W2) and at least the second electrical partial energy system (TEB2), in which for the energy transfer between the first and at least the second electrical partial energy system (TEB1, TEB2) - the first actuator (SG1) is controlled in such a way that a voltage is generated in the first winding (W1) by means of the first actuator (SG1), by means of which voltage a voltage is induced at least in the second winding (W2), whereby energy is transferred between the first and at least the second partial on-board energy network (TEB1, TEB2), wherein the voltage generated in the first winding (W1) is an alternating voltage whose voltage vectors are aligned in such a way that they contribute to a torque of at most + / - 5% of a nominal torque being generated in the rotor in addition to a target torque by the voltage generated in the first winding (W1) for the energy transfer.

Description

[0001] The invention relates to a method on the one hand and to a device for operating an on-board electrical system with a three-phase motor on the other hand.

[0002] On-board power systems in modern vehicles often have multiple on-board power system voltages, such as a conventional 12-volt voltage for standard consumers and / or an additional 12-volt voltage, for example, to decouple the voltage drop when the combustion engine starts from the rest of the on-board power system, and / or a higher voltage, for example, for functions such as increased recuperation or to supply high-power consumers. For this purpose, two or more decoupled partial power systems are used, which are coupled, for example, via a DC / DC converter to ensure an average charge level of the partial power systems.

[0003] DE 10 2005 044 341 A1 discloses an electric generator including a rotor, a stator, a rectifier, and a regulator. The rotor includes a field winding. The stator includes first and second three-phase windings, each of which has three output terminals corresponding to the respective phases. The rectifier has a three-layer structure to which the output terminals of the first and second three-phase windings are separately connected, and operates to output two different DC voltages by rectifying the outputs of the two three-phase windings.

[0004] DE 10 2005 026 779 A1 discloses an electric drive device comprising a multi-phase electric machine, a plurality of electric power output stages and means connected to the electric power output stages for controlling and / or regulating the electric machine, wherein at least two means for controlling and / or regulating the electric machine are present, wherein each means is assigned to at least one power output stage group.

[0005] US 6,617,820 B2 discloses a method for generating a low auxiliary voltage for electric or hybrid vehicles by tapping a voltage of a first winding of a traction motor with a second winding and a rectifier.

[0006] DE 10 2009 027 220 A1 relates to a device for supplying an electric drive for a motor vehicle with an energy network that is connected to the drive and has a fuel cell unit and at least one energy storage device, wherein the fuel cell unit and the energy storage device are coupled. According to the invention, the energy network has a first and a second energy network, the first energy network has a first converter arranged between the fuel cell unit and the drive, the second energy network has a second converter arranged between the energy storage device and the drive, and the first converter is decoupled from the second converter.

[0007] DE 10 2008 034 663 A1 relates to an electric drive system for a vehicle having a high-voltage battery and a low-voltage battery. The system comprises an AC electric motor and a double-ended inverter system coupled to the AC electric motor. The AC electric motor has a first set of windings and a second set of windings occupying common stator slots, the first set of windings and the second set of windings being electrically isolated from each other. The double-ended inverter system drives the AC electric motor using energy obtained from the high-voltage battery and energy obtained from the low-voltage battery.The double-ended inverter system uses a first inverter subsystem coupled between the first set of windings and the high-voltage battery, and a second inverter subsystem coupled between the second set of windings and the low-voltage battery.

[0008] The object underlying the invention is, on the one hand, to provide a method and, on the other hand, a device for operating an on-board electrical system which contributes to enabling energy transfer between a first and at least one second electrical partial energy system without galvanic coupling.

[0009] The problem is solved by the features of the independent patent claims. Advantageous embodiments are characterized in the subclaims.

[0010] The invention is characterized, on the one hand, by a method for operating an on-board electrical system and, on the other hand, by a corresponding device for operating an on-board electrical system. The on-board electrical system has a three-phase motor having a stator and a rotor, the stator having a first at least three-phase winding and at least one second at least three-phase winding, which are inductively coupled to one another. The on-board electrical system also has a first and at least one second electrical partial energy system. The on-board electrical system also has a first actuator that is electrically connected to the first winding and the first electrical partial energy system. The on-board electrical system also has at least one second actuator that is electrically connected to the second winding and at least the second electrical partial energy system.For energy transfer between the first and at least the second electrical partial power supply system, the first actuator is controlled such that a voltage is generated at the first winding by means of the first actuator, by means of which a voltage is induced in the second winding, whereby energy is transferred between the first and at least the second electrical partial power supply system. The voltage generated in the first winding is an alternating voltage whose voltage vectors are aligned such that a torque of at most + / - 5% of a nominal torque in addition to a target torque is generated in the rotor by the voltage generated in the first winding for energy transfer.

[0011] The on-board electrical system is, in particular, a multi-voltage on-board electrical system, particularly in a vehicle. A partial on-board energy system can have one or more energy storage devices and / or one or more energy sources and / or one or more consumers. The first and second partial on-board energy systems can have one or more energy storage devices and / or consumers and / or energy sources of the same or different types. Such energy storage devices are, for example, a lead-acid battery and / or a lithium-ion battery and / or a double-layer capacitor. Such energy sources are, for example, fuel cells. Such consumers can, for example, be powerful electric fans.

[0012] In this way, energy can be transferred from the first partial electrical power system to the second partial electrical power system and / or to additional partial electrical power systems without any galvanic coupling between the partial electrical power systems. Furthermore, no additional components are required, thus enabling very cost-effective energy transfer.

[0013] The voltage generated in the first winding is an alternating voltage whose voltage vectors are aligned in such a way that essentially no torque is generated in the rotor by the voltage generated in the first winding for energy transfer, in particular no torque is generated. In this context, "essential" means that if the motor is stationary, the rotor does not make any large movements, but only makes minimal rotational movements, such as + / - 30°. If the rotor is moving, it means in this context that the voltage generated in the first winding, for example per rotor revolution, generates no torque in the rotor, or only a very small torque, such as + / - 5% of a nominal torque, possibly in addition to a target torque. In this way, energy transfer can be achieved with a stationary or a rotating rotor.This can prevent, for example, the vehicle from moving unintentionally during the energy transfer if the three-phase motor is coupled to the vehicle's drive. By generating an alternating voltage, the rotor's inertia can also be utilized. The frequency of the alternating voltage is selected, for example, such that the rotor's inertia results in it generating essentially no torque during the energy transfer, in particular, no torque.

[0014] According to an advantageous embodiment, the voltage vectors of the generated voltage are aligned such that they are substantially perpendicular to a magnetic flux density of a magnetic excitation of the rotor. In this way, the rotor's orientation can also be advantageously utilized for energy transfer.

[0015] The axis along which the voltage vectors are essentially located, especially the q-axis, can also be referred to as the q-axis. It describes the torque to be generated by the rotor. The axis of the magnetic flux density can also be referred to as the d-axis.

[0016] According to an advantageous embodiment, the voltage vectors of the generated voltage are aligned such that they are substantially parallel to a magnetic flux density of a magnetic excitation of the rotor.

[0017] By aligning the voltage vectors of the generated voltage so that they are essentially parallel, in particular parallel to a magnetic flux density of a magnetic excitation of the rotor, the orientation of the rotor can also be advantageously used for energy transmission.

[0018] According to an advantageous embodiment, the first actuator has a circuit arrangement, wherein the circuit arrangement has at least three element groups connected in parallel. The element groups each have at least two individual elements connected in series. The individual elements each have a switching element and a diode connected in parallel. The first winding is electrically connected to the circuit arrangement such that each element group of the circuit arrangement is electrically connected between the individual elements to a phase of the first winding.

[0019] This allows the first actuator to be implemented in a simple and cost-effective manner.

[0020] According to a further advantageous embodiment, for energy transfer between the second and at least the first partial on-board power supply system, the second actuator is controlled such that a voltage is generated in the second winding by means of the second actuator, by means of which voltage is induced in the first winding, whereby energy is transferred between the second and at least the first partial on-board power supply system. The voltage generated in the second winding is an alternating voltage whose voltage vectors are aligned such that the voltage generated in the second winding for energy transfer essentially generates a torque of at most + / - 5% of a nominal torque in addition to a target torque in the rotor.

[0021] In this way, energy can be transferred from the first partial electrical on-board power system to the second partial electrical on-board power system, as well as from the second partial electrical on-board power system to the first partial electrical on-board power system and / or to further partial electrical on-board power systems.

[0022] For example, the voltage vectors of the voltage generated in the second winding are aligned so that they are perpendicular and / or parallel to the magnetic flux density of the rotor's magnetic excitation. In this way, the rotor's orientation can also be advantageously used for energy transfer.

[0023] According to a further advantageous embodiment, the second actuator has a circuit arrangement, wherein the circuit arrangement has at least three element groups connected in parallel, each of which has at least two individual elements connected in series. The individual elements each have a switching element and a diode connected in parallel. The second winding is electrically connected to the circuit arrangement in such a way that each element group of the circuit arrangement is electrically connected between the individual elements to a phase of the second winding.

[0024] This allows the second actuator to be implemented in a simple and cost-effective manner.

[0025] Embodiments of the invention are explained in more detail below with reference to the schematic drawing.

[0026] It shows: Fig. 1 an on-board network with a three-phase motor, a first and a second electrical partial energy network and a first and a second actuator.

[0027] Fig. 1 shows an on-board electrical system BN. The on-board electrical system BN is, in particular, a multi-voltage on-board electrical system of a vehicle. The on-board electrical system BN has a three-phase motor DM. The three-phase motor DM has a stator and a rotor. Fig. Figure 1 shows a separately excited three-phase DM motor in the form of a synchronous machine. Alternatively, other types of DM three-phase motors can be used, such as asynchronous machines and / or a separately excited, permanent-magnet, or a combination of separately excited and permanent-magnet synchronous machines or asynchronous machines.

[0028] The stator of the three-phase motor DM has a first winding W1 with at least three phases P1, P2, P3 and at least one second winding W2 with at least three phases P4, P5, P6. Fig.The windings W1 and W2 shown in Figure 1 are star windings. Alternatively, one of the two windings W1 and W2, or both windings W1 and W2, can be delta windings, or any other possible winding type. Instead of three-phase windings W1 and W2, windings W1 and W2 with more than three phases each can also be used.

[0029] The first three-phase winding W1 is inductively coupled to the second three-phase winding W2. The first winding W1 is electrically connected to a first actuator SG1.

[0030] The first actuator SG1 has a circuit arrangement, such as a so-called B6 bridge circuit, which has three element groups EG connected in parallel. The element groups EG each have two individual elements EE connected in series. The individual elements EE each have a switching element and a diode connected in parallel. The first winding W1 is electrically connected to the circuit arrangement in such a way that each element group EG of the circuit arrangement is electrically connected between the individual elements EE to a phase P1, P2, P3 of the first winding W1.

[0031] The second winding W2 is electrically connected to a second actuator SG2. The second actuator SG2 has a circuit arrangement, such as a so-called B6 bridge circuit, which has three element groups EG connected in parallel. The element groups EG each have two individual elements EE connected in series. The individual elements EE each have a switching element and a diode connected in parallel. The second winding W2 is electrically connected to the circuit arrangement in such a way that one element group EG of the circuit arrangement is electrically connected between the individual elements EE to a phase P4, P5, P6 of the second winding W2.

[0032] The first actuator SG1 and / or the second actuator SG2 and / or further actuators can alternatively be implemented as multilevel converters.

[0033] The first actuator SG1 is electrically connected to a first electrical partial energy system TEB1. The second actuator SG2 is electrically connected to a second electrical partial energy system TEB2. The first and second partial energy systems TEB1, TEB2 can be partial energy systems of different types, or alternatively, they can also be partial energy systems of the same type. Such partial energy systems TEB1, TEB2 have, for example, one or more energy storage devices and / or consumers and / or energy sources of the same or different types. Such energy storage devices are, for example, a lead-acid battery and / or a lithium-ion battery and / or a double-layer capacitor. Such energy sources are, for example, fuel cells. Such consumers can, for example, be powerful electric fans.

[0034] The first and second partial energy supply systems TEB1, TEB2 can, for example, have the same or different nominal voltages, such as 12V, 24V, 48V or other nominal voltages, or even nominal voltages above 60V.

[0035] The first actuator SG1 and the second actuator SG2 each optionally have a capacitor connected in parallel to the circuit arrangement for buffering high-frequency currents and / or for smoothing an output voltage.

[0036] The on-board electrical system BN further includes a control device SV. The control device SV comprises a computing unit, a data and program memory, and an interface to which it is signal-coupled for controlling the switching elements of the first actuator SG1 and / or the second actuator SG2.

[0037] The control device SV can also be referred to as a device for operating an on-board network.

[0038] The following describes an energy transfer between the first and the second electrical partial energy supply system TEB1, TEB2. In the same way, by appropriately controlling the second actuator SG2, an energy transfer between the second and the first electrical partial energy supply system TEB2, TEB1 is possible and / or into one or more further partial energy supply systems, and / or by appropriately controlling a further actuator, an energy transfer between the further actuator and the first electrical partial energy supply system TEB1 and / or the second electrical partial energy supply system TEB2 and / or further partial energy supply systems.

[0039] The first actuator SG1 is controlled in such a way that a voltage is generated in the first winding W1 by means of the first actuator SG1, by means of which a voltage is induced in the second winding W2, whereby energy is transferred between the first and at least the second partial on-board power supply system TEB1, TEB2, wherein the generated voltage in the first winding W1 is an alternating voltage whose voltage vectors are aligned in such a way that they contribute to the fact that essentially no torque is generated in the rotor by the voltage generated in the first winding W1 for energy transfer.

[0040] The generated voltage is an alternating voltage whose voltage vectors are aligned in such a way that they contribute to the fact that essentially no torque, in particular no torque, is generated in the rotor by the voltage generated for energy transfer in the first winding W1. The alternating voltage is generated by appropriately controlling the switching elements of the first actuator SG1. The voltage vectors of the generated voltage are aligned, for example, such that they are perpendicular to a magnetic flux density of a magnetic excitation of the rotor.

[0041] Alternatively or additionally, the voltage vectors can also be aligned so that they are parallel to the magnetic flux density of the magnetic excitation of the rotor. The axis of the magnetic flux density of the excitation of the rotor can also be referred to as the d-axis. The axis perpendicular to the d-axis, which describes the torque to be generated by the rotor, can also be referred to as the q-axis. The frequency of the generated alternating voltage is set, for example, in such a way that the inertia of the rotor is used, so that the voltage generated for energy transfer in the first winding W1 essentially generates no torque, in particular no torque. In this context, "essential" means that when the motor is at a standstill, the rotor does not make any large movements, but only executes at most small rotational movements, such as + / - 30°.In this context, if the rotor is moving, it means that the voltage generated in the first winding W1, for example, per rotor revolution, generates no or only a very small torque in the rotor, such as + / - 5% of a nominal torque, possibly in addition to a target torque. This allows energy transfer to be achieved with both a stationary and a rotating rotor. This can prevent the vehicle from moving undesirably during the energy transfer, for example, if the three-phase motor DM is coupled to the vehicle's drive.

[0042] This allows for simple energy transfer between the two partial on-board power systems TEB1 and TEB2 without galvanic coupling. Furthermore, no additional components are required, enabling energy transfer in a very cost-effective manner.

[0043] Galvanic decoupling also allows partial on-board power systems above the touch protection limit of 60V to be inductively coupled with partial on-board power systems below the touch protection limit of 60V, which is particularly useful in electric or hybrid vehicles. Furthermore, multiple partial on-board power systems with a nominal voltage above the touch protection limit can be inductively coupled with each other. This can also be used in electric and hybrid vehicles to achieve low-load, partial-load, or full-load operation on a three-phase motor with differently designed actuators SG1 and SG2. This can increase the efficiency of the traction drive in the individual phases.

[0044] If only energy transmission in one direction is desired, it may also be possible to dispense with the switching elements of the second actuator SG2 and / or the switching elements of the first actuator SG1. List of reference symbols BN on-board network DM three-phase motor EE single element EG element group TEB1 first partial energy system TEB2 second partial energy network SV control device SG1 first actuator SG2 second actuator W1 first winding W2 second winding P1-P6 phases

Claims

[1] Method for operating an on-board network (BN) with - a three-phase motor (DM) having a stator and a rotor, the stator having a first at least three-phase winding (W1) and at least one second at least three-phase winding (W2) which are inductively coupled to one another, - a first and at least one second partial electrical on-board power system (TEB1, TEB2), - a first actuator (SG1) which is electrically connected to the first winding (W1) and the first electrical partial energy system (TEB1), - at least one second actuator (SG2) which is electrically connected to at least the second winding (W2) and at least the second electrical partial energy system (TEB2), in which for the energy transfer between the first and at least the second electrical partial energy system (TEB1, TEB2) - the first actuator (SG1) is controlled in such a way that a voltage is generated in the first winding (W1) by means of the first actuator (SG1), by means of which voltage a voltage is induced at least in the second winding (W2), whereby energy is transferred between the first and at least the second partial on-board energy network (TEB1, TEB2), wherein the voltage generated in the first winding (W1) is an alternating voltage whose voltage vectors are aligned in such a way that they contribute to a torque of at most + / - 5% of a nominal torque being generated in the rotor in addition to a target torque by the voltage generated in the first winding (W1) for the energy transfer. [2] The method of claim 1, wherein the voltage vectors of the generated voltage are oriented to be substantially perpendicular to a magnetic flux density of a magnetic excitation of the rotor. [3] A method according to claim 1 or 2, wherein the voltage vectors of the generated voltage are aligned to be substantially parallel to a magnetic flux density of a magnetic excitation of the rotor. [4] Method according to one of the preceding claims, in which the first actuator (SG1) has a circuit arrangement, the circuit arrangement having at least three element groups (EG) which are connected in parallel and each having at least two individual elements (EE) which are connected in series, the individual elements (EE) each having a switching element and a diode connected in parallel, the first winding (W1) being electrically connected to the circuit arrangement in such a way that in each case one element group (EG) of the circuit arrangement is electrically connected between the individual elements (EE) to a phase (P1, P2, P3) of the first winding (W1). [5] Method according to one of the preceding claims, in which for the energy transfer between the second and at least the first electrical partial energy system (TEB2, TEB1) - the second actuator (SG2) is controlled in such a way that a voltage is generated in the second winding (W2) by means of the second actuator (SG2), by means of which voltage a voltage is induced at least in the first winding (W1), whereby energy is transferred between the second and at least the first partial on-board energy network (TEB2, TEB1), wherein the voltage generated in the second winding (W2) is an alternating voltage whose voltage vectors are aligned in such a way that they contribute to a torque of at most + / - 5% of a nominal torque being generated in the rotor in addition to a target torque by the voltage generated in the second winding (W2) for the energy transfer. [6] Method according to one of the preceding claims, in which at least the second actuator (SG2) has a circuit arrangement, the circuit arrangement having at least three element groups (EG) which are connected in parallel and each having at least two individual elements (EE) which are connected in series, the individual elements (EE) each having a switching element and a diode connected in parallel, the second winding (W2) being electrically connected to the circuit arrangement in such a way that in each case one element group (EG) of the circuit arrangement is electrically connected between the individual elements (EE) to a phase (P4, P5, P6) of the second winding (W2). [7] Device for operating an on-board network (BN), wherein the device is designed to carry out a method according to one of claims 1 to 6.

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