DE102018221455A1 - Circuit arrangement for electrical energy supply in a vehicle - Google Patents

Abstract

The invention relates to a circuit arrangement (100) for supplying energy to an electrical machine (120) for a vehicle, which has a first inverter (111) and a second inverter (112), and a first winding (121) with a first central point (144). and a second winding (122) having a second central point (145) separated from the first central point (144). The first inverter (111) is connected to the first winding (121) and the second inverter (112) to the second winding (122). The first inverter (120) is set up for connection to a first energy source (101) and the second inverter (122) is set up for connection to a second energy source (102).

Description

The present invention relates to a circuit arrangement and a method for electrical energy supply in a vehicle. In addition, the present invention relates to a motor vehicle, which comprises such a circuit arrangement for electrical power supply.

Many of the electrical components, including electrical motors used in vehicles, receive electrical power from AC power supplies. The energy sources (e.g. energy sources) which are used in such applications, however, only supply direct voltage or direct current. Therefore, devices that are known as “inverters / rectifiers” are used to convert the DC voltage to AC voltage and are referred to below as inverters or inverters, which often use multiple switches or transistors that are operated at different intervals to convert the DC voltage into AC voltage convert.

In addition, vehicles of the type of interest here, particularly fuel cell vehicles, often use two separate energy sources (e.g. an energy source and a fuel cell) to power the electric motors that drive the wheels. Typically, voltage converters, such as DC / DC converters, are used to manage and transmit the power from the two energy sources. Modern DC / DC converters often include transistors that are electrically connected by an inductor. By controlling the states of the various transistors, an average target current can be impressed through the inductance and thus control the power flow between the two energy sources.

The use of both an inverter and a power converter significantly increases the complexity of the electrical system of the motor vehicle and thus increases the probability of failure of the drive system.

The background of the invention lies in the fact that a reliable drive system is necessary, particularly in autonomous driving. In the case of the electric drive systems currently known in the prior art, if a simple error occurs, the next workshop or a next parking space can be driven on with mostly reduced drive power. In autonomous driving in particular, however, it is required that the vehicle remain fully usable if a simple error occurs.

Disclosure of the invention

It is therefore the object of the present invention to provide a circuit arrangement for energy supply with which a probability of failure is significantly reduced.

The object is achieved by a circuit arrangement for the electrical energy supply in a vehicle and a vehicle having such a circuit arrangement in accordance with the independent claims. The dependent claims, which refer back in each case, represent advantageous developments of the invention.

According to one aspect of the invention, a circuit arrangement for supplying energy to an electrical machine for a vehicle is proposed, comprising: a first inverter and a second inverter, and also a first winding with a first central point and a second winding with a second central point, which is from the first central point is separated. The first inverter is connected to the first winding and the second inverter to the second winding. The first inverter is set up for connection to a first energy source and the second inverter is set up for connection to a second energy source.

An energy source can in particular be a battery or an accumulator, or e.g. a fuel cell.

Winding is understood to mean wound electrical conductors for generating a magnetic field. The magnetic field serves e.g. in a motor or in an electrical machine by converting the drive into mechanical energy or in a generator by converting it into electrical energy for generating electricity. Windings have inductive properties in particular, which is why they are also used for coils or induction. Inductors used in particular in circuits are used to convert electrical to magnetic energy and vice versa, or for short-term storage of electrical energy in the form of magnetic energy. In this description, the term “winding” is used for the winding in an electrical machine, wherein a winding of a motor can have several phase windings. For example, a three-phase controlled motor has three phase windings. The three phase windings are referred to here as one winding (of the electrical machine).

It should also be noted that electrical machines can also work as generators.

The energy supply of an electrical machine for a vehicle is according to the above aspect provided by the first energy source individually, the second energy source individually or by both energy sources simultaneously. For this purpose, a first energy source, for example an accumulator, forwards electrical energy to a winding by means of an inverter. A second energy source, which can differ from the first, similarly transfers energy to the second winding via a second inverter unit. The inverters each have several, for example three, electrical phases, each of which is connected to a phase winding, so that the phase windings which form the electrical machine for the electrical drive of the vehicle are supplied with energy. An inverter represents an inverter, whereby each of the two inverters can be a 2-level or a multilevel inverter.

The first and second energy sources are connected, for example, by switches. The switches can be used to select which energy source or which inverter supplies the electrical machine with energy. If there is a fault in one branch, the energy can be provided via the remaining branches.

The phase windings of the first and second windings are wound in such a way that they each have a central point. The central point of the first winding is separated from the central point of the second winding. Both inverters can be used to supply the electrical machine with electricity and to charge the energy sources. The phase windings can have, for example, two three-phase windings, which can be geometrically offset at any angle and can have a different number of windings. They can also be clocked at any time.

The circuit arrangement can thus be used to drive the vehicle, but also to charge the first or the second energy source, as shown in the embodiments.

According to one embodiment, the first inverter is switchably connected to the second inverter for charging an energy source or for combinatorial use of the first and / or second inverter for driving an electric motor. To use both energy sources or inverters at the same time or an energy source with any inverter individually for driving the electric motor, the inverters are connected to one another. As a result of the switchability, the electrical drive is supplied with energy with the three phases of a winding or with the six phases in total of both windings, so that a six-phase electrical machine is formed which is operated either in three-phase or in six-phase.

According to one embodiment, the first inverter has a first positive supply line and the second inverter has a second positive supply line, and the first inverter and the second inverter are connected to the first and second positive supply lines by a switch for combinatorial use of the connected first and / or second inverter for driving an electric motor.

This means that the switches create different ways of assigning the energy sources to the inverters. For example, the first energy source can supply energy for the first inverter and the second inverter and the electrical machine can be operated with a six-phase energy source, or the first energy source can only supply the energy for the second inverter when the first inverter is not operated, so that the electrical Machine is operated three-phase with the phase windings of the second winding.

The inverters can have a common electrical potential. If this is not the case due to the electrical connection, this is provided by connecting the negative supply line of the first inverter to the negative supply line of the second inverter. This connection can be implemented using an additional switch, e.g. simultaneously with the switch that connects the positive supply lines to each other.

Depending on their intended use, the switches can be either mechanical or electromechanical switches, e.g. Relays or contactors, as well as electronic switches, e.g. IGBT or MOSFET.

The circuit arrangement has the advantage that the various possible combinations of the energy sources with the inverters, which can be used to supply power to the vehicle, produce redundancy, and thus the reliability with regard to the electrical energy supply of the system is significantly increased. If an inverter fails or an energy source fails, the vehicle can continue to be operated with the second energy source or with the second inverter.

Another advantage is that the electrical machine can be operated at an efficient operating point. Due to the possible extraction of energy from two energy sources and the use of two inverters, an optimal operating point of the energy store can be approached, while at the same time protecting the components by lower utilization, which, for example, reduces aging and becomes one leads to a longer service life and also reduces energy losses.

In one embodiment, the first inverter is connected to the second inverter through a central point connection switch connected to the first and second central points. This switchable connection can be used to switch between using the inverter circuit to drive the vehicle and charging an energy source.

According to one embodiment, when the central point connection switch is closed, the first inverter is galvanically connected to the second inverter via the first winding and the second winding, and both the first and the second inverter are set up as DC voltage converters for bidirectional DC voltage conversion for charging an energy source. In this case, the energy source is charged when the vehicle is not being driven or is at rest. Due to the galvanic connection, the first energy source can charge the second energy source via the DC converter or converters. This is particularly advantageous in the case of hybrid energy sources if one of the energy sources is a fuel cell and the other is an alkaline or transition metal-based accumulator. The inverters can be used as step-up converters or as step-down converters.

According to one embodiment, when the central point connection switch is open, the first inverter is connected inductively to the second inverter via the first and the second winding. The first inverter is set up to drive the motor, and the second inverter is set up to act as a DC-DC converter in order to generate a charging voltage for charging an energy source from the induced voltage. That is, by this embodiment, while the vehicle is being driven, the second power source via the windings and the second inverter can be charged by the first power source.

The inverters contain switches that are electronically controlled. So-called free-wheeling diodes are usually arranged in parallel with the switches, which derive current peaks that arise during switching. Electronic components can contain integrated protective diodes that take over the freewheeling function.

According to one embodiment, the first winding and / or the second winding is in each case of a multi-phase connection in a delta connection and the first or the second central point is a point of a delta connection.

According to one embodiment, the first winding and / or the second winding are each made of multiple phases in a star connection and the first or the second central point is a point of a star connection.

While a delta connection can provide a higher motor power than star connections due to the higher voltages at the inductors, star connections require a significantly lower starting current. A combination of star and delta connection to a so-called star-delta starting circuit is therefore particularly advantageous, so that first the low starting current of the star connection can be used and then switched to delta connection or the delta connection is switched on in order to thereby drive the energy through to use both energy sources.

According to a further embodiment, the energy sources are of the same type or different types. designed as fuel cells, supercapacitors or accumulators based on alkali or transition metal. Alkali or transition metals are, for example, nickel, sodium or lithium. The energy sources can therefore also be a combination of medium temperature, high energy and high performance energy sources.

The switches of the circuit arrangement can be electronic, electromechanical or mechanical. Electronic switches are, for example, transistors, e.g. IGBTs and MOSFETs. Electromechanical switches are e.g. Relay.

According to one aspect, a motor vehicle is provided which has a circuit arrangement described above. Motor vehicles can be, for example, electric cars, buses, trucks, trains, self-propelled work machines, electric planes or electric boats. The land vehicles can be rail-bound vehicles or vehicles with overhead lines. For example, in a vehicle with axles, the energy sources could be located near the axles.

The electrical energy can thus be provided by, for example, two energy sources of the same or different types. When the car is driving, the energy of the electrical machine is provided in a suitable form via the inverters and the windings in order to drive the vehicle, or one energy source can be provided by the other in one configuration during driving operation and in another configuration during the idle phase of the vehicle. The double design of the units and their switchable connection creates redundancy so that if an error occurs in one of the two Partial arrangements the vehicle can continue to drive with the other partial arrangement. If the error is that one of the two energy sources needs to be charged, this can be remedied.

• 1 ein Blockschaltbild einer Schaltungsanordnung zur Energieversorgung eines elektrischen Antriebssystems gemäß einem Ausführungsbeispiel,
• 2 ein Blockschaltbild einer Energiequelleanordnung gemäß einem Ausführungsbeispiel,
• 3 ein Blockschaltbild eines Inverters gemäß einem Ausführungsbeispiel,
• 4 eine Schaltungsanordnung von Wicklungen gemäß einem ersten Ausführungsbeispiel,
• 5 ein Schaltungsanordnung von Wicklungen gemäß einem zweiten Ausführungsbeispiel,
• 6 ein Diagramm, das die Kennlinie des Moments in Abhängigkeit der sechsphasigen elektrischen Maschine zeigt,
• 7 ein Kraftfahrzeug gemäß einem Ausführungsbeispiel.

Embodiments of the invention are shown in the figures and explained in more detail in the following description. Show it:

• 1 2 shows a block diagram of a circuit arrangement for supplying energy to an electrical drive system according to an exemplary embodiment,
• 2nd 2 shows a block diagram of an energy source arrangement according to an exemplary embodiment,
• 3rd 2 shows a block diagram of an inverter according to an exemplary embodiment,
• 4th 1 shows a circuit arrangement of windings according to a first exemplary embodiment,
• 5 1 shows a circuit arrangement of windings according to a second exemplary embodiment,
• 6 a diagram showing the characteristic curve of the torque as a function of the six-phase electrical machine,
• 7 a motor vehicle according to an embodiment.

1 shows a circuit arrangement 100 for the energy supply of an electric drive system according to an embodiment. The circuit arrangement shown has two energy source arrangements 101 , 102 , two inverters 111 , 112 and two windings 121 , 122 on. The first winding also has a first central point 144 on and the second winding a central point 145 . Central point is understood here to mean a point of the multiphase winding which has a common potential with two or more ends of a phase winding. The energy source arrangements 101 , 102 are with the inverters 111 , 112 over the lines 103 , 105 or. 104 , 106 connected, and this in turn via the lines 131 , 133 , 135 or. 132 , 134 , 136 with the windings 121 and 122 . The windings 121 and 122 together form the electrical machine 120 .

2nd shows the energy source arrangement 101 with an energy source 201 and shooters 203 and 205 . The energy source arrangement 102 can have the same or a similar structure. With the shooters 203 , 205 can be the energy source 201 from the inverter 111 be separated or connected to it. Analogously, the second energy source of the energy source arrangement 102 from the inverter 112 be separated or connected to it, so that the electrical machine with three phases 131 , 133 , 135 either the winding 121 or three phases 132 , 134 , 136 the winding 122 is operated or six-phase with both windings 121 , 122 .

3rd shows an example of the inverter 111 of the 1 with the switch arrangement 301 , which represents a simple so-called B6, i.e. a 6-bridge inverter. However, it is also possible to use further switch arrangements known to the person skilled in the art, such as two-level or multilevel inverters designed with MOSFETs, IGBTs, protective diodes, etc.

As in 1 also shown are the power source arrangements 101 , 102 on the one hand directly via the switches 141 or. 142 interconnectably connected and on the other hand via switches 143 .

If the electrical machine is not currently being operated to drive the vehicle, for example when the vehicle is stationary, then the circuit arrangement can 301 ( 3rd ) of the inverter unit in combination with the phase windings with the switch open 141 ( 1 ) can also be operated as a DC converter. The DC voltage conversion can be due to the mirror symmetry of the branches 101 , 111 , 121 or. 102 , 112 , 122 occur in both directions and thereby take place both as an upward conversion and as a downward conversion. The top switches of the circuit arrangement 301 and switches 143 can, for example, be closed and the lower switches open, so that the phase lines 131 , 133 , 135 are connected to the positive pole of the energy source, while a voltage conversion in the other branch 102 , 112 , 122 takes place.

4th and 5 show examples of the windings 121 , 122 . In 4th is an embodiment with a three-phase star connection 401 , 402 illustrated. The central points with a common potential at one end of the individual phase windings are the star points 144 and 145 .

5 shows a combination of a star connection 501 with central point 144 and a delta connection 502 with central point 145 . Star and delta connections have different properties, such as a higher starting current for the star connection and a higher coil voltage for the delta connection 502 , which can be advantageously combined by the circuit arrangement shown. However, other circuit arrangements and combinations are also possible, such as two delta or star connections, parallel connections, possibly with additional switches, etc.

4th and 5 continue to assign the switch 143 on the the two windings 111 , 112 about the central points 144 and 145 connects with each other.

With the circuit arrangement 100 one of the two energy sources can be charged by the other energy source. The windings act as a transformer, the windings in one winding being the primary side and inducing voltage in the windings of the other winding. For this purpose, the switch is used while driving 143 open. The winding 121 works as an engine, for example. The phase windings 131 , 133 and 135 are energized and induce a voltage in the phase windings 132 , 134 , 136 . The winding 122 then acts as a generator and by means of the inverter 112 , which is clocked as a rectifier, becomes the energy source of the energy source arrangement 102 loaded.

When the vehicle is at rest, an energy source can be charged via either the direct or indirect connection.

6 shows a diagram with characteristic curves of the moment 601 depending on the speed 602 the six-phase electrical machine. The characteristic 603 describes the characteristic curve when operating the electric motor with both three-phase windings, characteristic curve 604 when operating the electric motor only with the second three-phase winding and characteristic 605 when operating the electric motor only with the first three-phase winding. The moment size depends on the current or the motor voltage, or on the energy source voltage and the inverter modulation index. The key points 606 , 607 , 608 depend on the number of turns of the three-phase windings. The electric machine can be operated in partial load operation at the optimal operating point from the optimal source. For example, an operating point on the characteristic 605 can be selected if only a low torque is required.

7 shows by way of example a vehicle according to an embodiment, which has a circuit arrangement described above for the electrical energy supply in a vehicle.

Claims (9)

Circuit arrangement (100) for supplying energy to an electrical machine (120) for a vehicle, comprising: a first inverter (111) and a second inverter (112), a first winding (121) with a first central point (144) and a second winding (122) with a second central point (145) which is separated from the first central point (144), in which the first inverter (111) is connected to the first winding (121) and the second inverter (112) is connected to the second winding (122), and wherein the first inverter (111) is set up for connection to a first energy source (101) and the second inverter (112) is set up for connection to a second energy source (102). Circuit arrangement (100) after Claim 1 , wherein the first inverter (111) is switchably connected to the second inverter (112) for charging an energy source or for combinatorial use of the first (111) and / or second (112) inverter for driving an electric motor. Circuit arrangement (100) according to one of the preceding claims, wherein the first inverter (111) has a first positive supply line (103) and the second inverter (112) has a second positive supply line (104), and the first inverter (111) and the second Inverter (112) by a switch (141) which is connected to the first (103) and to the second (104) positive supply line for combinatorial use of the first (111) and / or second (112) inverter for driving an electrical one Motors (120) is connected. Circuit arrangement (100) according to one of the preceding claims, wherein the first inverter (111) is connected to the second inverter (112) by a central point connection switch (143) which is connected to the first (144) and to the second (145) central point is. Circuit arrangement (100) after Claim 4 wherein the first inverter (111) is electrically connected to the second inverter (112) via the first winding (121) and the second winding (122) when the central point connection switch (143) is closed, and both the first (111) and the second Inverter (112) is set up as a DC-DC converter for bidirectional DC-voltage conversion for charging an energy source. The circuit arrangement (100) according to claim 46, wherein the first inverter (111) is openly connected to the second inverter (112) via the first and second windings (122) when the central point connection switch (143) is open, and the first inverter (111) is set up is to drive the motor, and the second inverter (112) is set up to act as a direct voltage converter in order to generate a charging voltage for charging an energy source from the induced voltage. Circuit arrangement (100) according to one of the preceding claims, wherein the first winding (121) and / or the second winding (122) is in each case made of three phases in a delta connection (502) and the first (144) or the second (145) central point Point of a delta connection (502). Circuit arrangement (100) according to one of the preceding claims, wherein the first winding (121) and / or the second winding (122) is in each case multi-phase in star connection (401, 402, 501) and the first or the second central point is a point Star connection (401, 402, 501). Motor vehicle (700) which has a circuit arrangement (100) according to one of the Claims 1 to 7 having.

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