DE102010050347B3 - Device for producing secure operating condition of high-voltage intermediate circuit of e.g. lorry, has discharge switches separately arranged in current paths, and trigger device actuating circuit breakers based on state signal of vehicle - Google Patents

Abstract

The device has two additional discharge current paths formed between connection poles of an intermediate circuit capacitor and for discharging the capacitor during separation of circuit breakers (19, 20). Discharge switches (28, 29) are separately arranged in the current paths to close the current path. Each switch is coupled with the associated circuit breaker so that opening of the circuit breaker causes closing of the respective current paths by the switches. A trigger device (17) actuates the circuit breakers based on a state signal (18) of an electric vehicle (1). Independent claims are also included for the following: (1) an electric vehicle comprising a high-voltage intermediate circuit (2) a method for producing a secure operating condition of a high-voltage intermediate circuit of an electric vehicle.

Description

The invention relates to a device for producing a safe operating state of a high-voltage intermediate circuit of an electric vehicle, wherein the high-voltage intermediate circuit is fed from a supply unit and the high-voltage intermediate circuit has an intermediate circuit capacitor which feeds an electric motor, wherein at least one circuit breaker is provided to separate the supply unit from the high-voltage intermediate circuit ,

The invention also relates to a method for producing a safe operating state of a high-voltage intermediate circuit of an electric vehicle, wherein a supply unit of a high-voltage intermediate circuit supplying an electric motor is galvanically separated from the high-voltage intermediate circuit as a function of a vehicle condition signal.

The invention further relates to an electric vehicle, wherein a high-voltage intermediate circuit is fed from a supply unit and the high-voltage intermediate circuit has an intermediate circuit capacitor which feeds an electric motor, wherein at least one disconnecting switch is provided to separate the supply unit from the high-voltage intermediate circuit.

An electric vehicle is generally understood to mean a vehicle which has at least one electrically driven drive motor. The vehicle can therefore be driven exclusively electrically, or it can be provided with a combination engine of an electric drive motor with an internal combustion engine. For example, in a land vehicle, the internal combustion engine may drive the front wheels while the electric drive motor is driving the rear wheels of the land vehicle, or vice versa. It can also be provided that both the electric drive motor and the internal combustion engine drive a common wheel or drive axle - that of the front wheels and / or the rear wheels or a drive means.

The supply unit can be designed as a battery, as a secondary winding of a system for inductive power supply, as an internal combustion engine or in any other way. The supply unit provides a supply voltage through which the high voltage intermediate circuit is fed.

It is known to equip vehicles with sensors for detecting a vehicle condition, which generate a vehicle condition signal in the event of a crash or the like. This vehicle condition signal is used in known vehicles to trigger securing means such as airbags and / or to make emergency calls.

In electric vehicles, in which a high-voltage intermediate circuit is fed from a supply unit, the high voltage of the intermediate circuit is an additional danger in the event of an accident or accident. In particular, as a result of the accident or accident, the high voltage to body parts lie, or it can unwanted power line come in a fire extinguisher. In this application, high voltages are voltages above 50 V, in particular between 70 V and 1000 V understood.

In order to minimize the danger emanating from the supply unit, it is known to separate the high-voltage intermediate circuit between the supply unit and the electric motor of the supply unit. For this purpose, a circuit breaker is often provided, which is opened by the mentioned vehicle condition signal.

Since modern electric drives are designed as controlled electric motors, power electronics are often connected to the high voltage intermediate circuits, which drives the motor with a high-frequency switching signal. In order to prevent this switching signal unnecessarily loading the supply unit, an intermediate circuit capacitor is provided in the high-voltage intermediate circuit for smoothing the feedback from the power electronics to the supply unit.

From the DE 10 2007 047 713 A1 a device for discharging a high voltage network is known, in which an auxiliary switch is to prevent the danger of short circuit during switching and should serve to selectively control a discharge of the capacitances in the DC intermediate circuit, if this is necessary.

From the JP 2000-078851 A there is known a positively driven DC link capacitor discharge apparatus in which the voltage on the link capacitor is monitored to detect a molten relay.

From the JP 09-070196 A For example, a discharger for an internal electricity storage means of an inverter is known in which a control unit, after disconnecting a battery, sets an excitation current which generates a torque equal to zero until a capacitor of the storage means is discharged.

From the DE 10 2007 022 515 A1 are a method and an apparatus for operating a Control unit for controlling an electrical machine known, wherein a rapid discharge of the DC link capacitor is controlled by driving an inverter.

From the US 2004/0008530 A1 a control device of an inverter for an electric vehicle is known, in which the charge collected on a smoothing capacitor is discharged by means of a high-frequency voltage which is supplied to the stator windings of the rotor by appropriate control of the inverter.

From the DE 10 2008 010 980 A1 a method and a device for discharging a high-voltage network are known, wherein first a battery is disconnected by means of a switch from the rest of the electrical system and wherein thereafter a resistor and at the same time one or more high-voltage consumers are turned on.

From the DE 10 2008 061 585 A1 For example, a vehicle with a supply device for an electric motor and a method for supplying power to the electric motor are known, wherein a discharging device converts the stored electrical energy into heat energy when unloading a buffer device.

From the US Pat. No. 5,994,789 A a control system for an electric vehicle is known, in which the link capacitor is discharged by a secondary battery is charged with the stored energy.

From the DE 10 2006 043 950 A1 a device for rapid discharge of capacitors is known, with the help of the rapid discharge can be done at predetermined conditions and battery disconnected via two in a current path in series with the battery changeover switch, the changeover switches are designed so that two of their switching contacts via a Connection are coupled.

The invention has for its object to improve the production of a safe operating state of a high voltage intermediate circuit of an electric vehicle.

This object is achieved in a device of the type mentioned by the features of claim 1, in an electric vehicle by the features of claim 8 and in the method of the type mentioned by the features of claim 9.

According to the features of claim 1 are provided for solving the problem in a device of the type mentioned. Thus, it is provided in particular that an additional discharge current path is formed between the connection poles of the intermediate circuit capacitor, which is set up for discharging the intermediate circuit capacitor when the separation switch is disconnected. It is advantageous in this case that this discharge current path can neutralize the charge stored on the intermediate circuit capacitor by means of a discharging process as soon as the disconnecting switch is disconnected in the event of an accident. Thus, it can be avoided with great certainty that the high voltage values of the DC link capacitor represent a danger for rescue personnel or passengers of the electric vehicle. A current path is understood as a circuit along which an electric current can flow.

Preferably, the additional discharge current path is formed in parallel with the electric motor. Thus, the electric motor is short-circuited by the discharge current path. The electric motor is thus disabled in case of accident and is no source of danger due to sudden loss.

According to the invention, it is further provided that the at least one circuit breaker is operatively connected to a relay. Preferably, the relay disconnects the at least one disconnect switch in the de-energized state. The advantage here is that the circuit breaker is safely placed in the event of an accident in the disconnecting switching state.

According to the invention it is further provided that in the additional discharge current path, a discharge switch is arranged, which is assigned to the at least one circuit breaker. The advantage here is that the Entladestrompfad can be interrupted in normal operation. In order to activate the discharge current path, it may be provided that the discharge switch is coupled to the at least one disconnect switch such that opening the disconnect switch causes the discharge current path to close via the discharge switch. This ensures that the DC link capacitor is discharged in every case of an accident.

According to the invention, it is further provided that the coupling between disconnector and associated discharge switch is mechanically formed. The advantage here is that the necessary to activate the Entladestrompfades actuation of the discharge switch also works safely when the electrical power supply of the electric vehicle is out of order.

According to the invention, it is further provided that each terminal pole of the supply unit can be separated from the high-voltage intermediate circuit by a respective disconnector. In this case can be provided that each circuit breaker is assigned a separate discharge switch.

For this purpose, it is provided that each discharge switch closes an associated Entladestrompfad alone. Thus, although the number of required Entladestrompfade increases, however, it can be discharged even when one of the circuit breaker does not work properly, the DC link capacitor. Thus, the safety of the electric vehicle is increased again.

For faster destruction of the electrical energy stored in the intermediate circuit capacitor as a charge, an electrical load can be arranged in the discharge current path.

For example, the electrical load may have an ohmic resistance. This resistor is formed in a preferred embodiment as a PTC thermistor or PTC resistor and thus generally as a temperature-dependent, ohmic resistor with high conductivity at low temperatures and low conductivity at higher temperatures. The advantage here is that the electrical load itself heats up in the discharge process by the discharge current, whereby the current flow opposite resistance increases. This results in a slowing of the discharge process until the resistor has cooled down again. This results in a pulsating discharge current curve, which prevents overloading of the discharge current path in a simple and effective manner.

In one embodiment, the electrical load comprises a rotor excitation of the electric motor. In this case, provision can be made, in particular, for the discharge current path to be configured for the reactive current injection of the rotor. In this way, it can be easily achieved that the discharge current flowing to destroy the stored energy does not generate any torque at the electric motor, but energizes the d axis. In this way, unwanted movements of rotating parts are avoided in the event of an accident.

Alternatively or additionally, it can be provided that the electrical load comprises a stator current supply of the electric motor. Again, it may be provided that the current is set up so that no torque is formed in the electric motor.

The electrical load may also be a DC / DC controller between the DC link and a low voltage circuit. Such low-voltage circuits are also used in electric vehicles with high-voltage intermediate circuits for the electrical operating parts, which should be accessible to the layman. Examples include vehicle lighting and consumer electronics and control electronics. It can be provided that the electrical load is permanently connected to the DC link capacitor and thereby automatically forms a discharge path in the event of an accident. It can also be provided that additional components of the DC / DC adjuster are connected to form a discharge current path.

For example, this can be achieved by arranging at least two DC / DC regulators in parallel with a correspondingly reduced (halved) nominal power in order to obtain redundancy. These DC / DC controllers can be switched on individually or jointly to form the discharge current path.

For safe release of the device according to the invention in case of accident, a triggering device is provided, which actuates the at least one disconnect switch in response to a vehicle condition signal. The advantage here is that the separation of the supply unit and the discharge of the DC link capacitor automatically done in case of accident, so that the sources of danger, which are formed by the high-voltage components, can be eliminated.

In order to achieve the shortest possible transmission paths and secure couplings, it can be provided that the at least one disconnect switch and / or the discharge switch is arranged in spatial proximity to the supply unit / are. Here, spatial proximity is understood to mean a distance that is less than half, preferably less than a quarter or even less than one-tenth, of the vehicle length. In this way it can be achieved that the connecting lines between the supply unit and the circuit breaker need not be performed by the whole vehicle, which would be an additional source of danger. It is particularly advantageous if the circuit breakers for the supply unit are integrated into a housing of the supply unit.

For a uniform load of the electric vehicle, the electric drive and the supply unit are often arranged at opposite ends of the vehicle. For example, in a front-wheel drive the electric motor can be arranged in the front part of the vehicle, while the supply unit, ie the battery, is integrated in the rear area of the vehicle or in the floor of the vehicle. In a rear-wheel drive, these conditions are reversing. Often, the DC link capacitor in the vicinity of the power electronics or the power units for the control of the electric motor. In these cases, the invention can provide that the at least one disconnecting switch and / or the at least one discharging switch are arranged in that vehicle part in which the supply unit and / or the intermediate circuit capacitor is / are located.

The described device according to the invention can be advantageously used in an electric vehicle, in which a sensor is designed for detecting a vehicle condition, wherein a dependent on the vehicle condition sensor or Fahrzeugzeustandssignal the sensor controls the at least one disconnector. In the case of a coupling according to the invention between disconnector and a discharge switch thus the vehicle condition signal also controls the discharge switch.

To achieve the above object, the features of claim 9 are provided in the aforementioned method for producing a safe operating state of a high voltage intermediate circuit of an electric vehicle. In particular, it is provided that after the galvanic isolation of the high voltage intermediate circuit from the supply unit, an intermediate circuit capacitor of the high voltage intermediate circuit is discharged via an additional discharge current path.

It is preferably provided here that the discharge circuit is closed simultaneously with the separation of the supply unit.

Preferably, the use of a device according to the invention is provided for this purpose.

The method according to the invention and the device according to the invention can be advantageously used in the operation of an electric vehicle.

In the following the invention will be described in more detail with reference to an embodiment. Here, the invention is not limited to the embodiment. Further embodiments result from combining one or more features of the claims with each other and / or with one or more features of the embodiment.

LIST OF REFERENCE NUMBERS

1

electric vehicle

2, 3

wheel

4

axis

5

transmission

6

drive unit

7

electric motor

8th

supply unit

9

High voltage link

10

first power section

11

second power section

12

exchangers

13

Rotor position encoder

14

Link capacitor

15, 16

Connection pole of 8th

17

triggering device

18

Vehicle condition signal

19, 20

disconnectors

21, 22

relay

23, 24

Connection pole of 14

25, 26

discharge current

27

Three-phase line

28, 29

discharge

30, 31

coupling

32

electrical consumer

33

PTC resistor

34

DC / DC controller

35

Low-voltage battery

It shows

1 a schematic representation of an electric vehicle and

2 a schematic circuit diagram of a device according to the invention.

1 shows in a schematic view from above as a whole with 1 designated electric vehicle. Shown are the components relevant to the explanation of the invention as a block diagram, while others, for the proper functioning of the electric vehicle 1 required, known per se components have been omitted for ease of illustration.

The electric vehicle 1 has four wheels 2 . 3 on. In other embodiments, two- or three-wheel configurations are provided.

The electric vehicle 1 can be designed as a car or truck and rail-bound or freely controllable.

In 1 is an electric vehicle 1 shown at which the wheels 3 are driven as rear wheels. In this case, the wheels can 2 be steerable as front wheels. However, other configurations are possible for carrying out the invention, in which, for example, the driven wheels are simultaneously suspended steerable.

The axis 4 which the wheels 3 carries, gets over a gearbox 5 through the drive unit 6 for moving the electric vehicle 1 driven.

Optionally existing differentials are not shown for simplicity.

The drive unit 6 has an electric motor 7 on, which from a supply unit 8th about one in 1 not further apparent, but in 2 High voltage intermediate circuit shown in detail 9 is fed.

The supply unit 8th is formed in the embodiment shown as a high voltage battery, in other embodiments, the supply unit comprises 8th the secondary-side, resonant wiring of an inductive power supply system.

In the embodiment shown, the electric motor 7 a foreign-excited synchronous machine. Accordingly, a first power section 10 provided with power electronics for driving and energizing the stator windings and thus for generating the stator field, and it is a second power unit 11 formed with power electronics for energizing the rotor and thus for generating and controlling the rotor field.

A known transformer 12 serves the coupling of the rotor current.

To control is also a rotor position sensor 13 intended.

The power parts 10 . 11 are operated on the principle of pulse width modulation, resulting in an undesirable in itself feedback via the high voltage intermediate circuit 9 on the supply unit 8th would result.

To the resulting from this reaction load on the supply unit 8th to reduce, is in the high voltage intermediate circuit an intermediate circuit capacitor 14 between the connection poles 15 . 16 the supply unit 8th arranged, cf. 2 , The DC link capacitor 14 thus causes a smoothing of the pulsating reaction.

To recognize special vehicle conditions, such as accidents or crashes, has the electric vehicle 1 in a conventional manner via a triggering device 17 which, upon the occurrence of the particular vehicle condition, a sensor signal as a vehicle condition signal 18 generated. This vehicle condition signal 18 is often used to deploy the airbags.

As shown, the vehicle condition signal causes 18 for a safe deactivation of the drive unit 6 , On the other hand, the vehicle condition signal acts 18 on disconnector 19 . 20 which is indicated by the vehicle condition signal 18 the supply unit 8th from the high voltage intermediate circuit 9 and thus of the power parts 10 . 11 separate.

Every disconnector 19 . 20 is there with a relay 21 . 22 connected, which in the de-energized state the respective disconnector 19 . 20 opens.

For discharging the DC link capacitor 14 with disconnectors open 19 . 20 are between the connection poles 23 . 24 of the DC link capacitor 14 two discharge current paths 25 and 26 educated.

The discharge current paths 25 . 26 are thus parallel to the electric motor 7 or the power parts 10 . 11 that the electric motor 7 over a three-phase line 27 supply, arranged.

In each discharge current path 25 . 26 is a discharge switch 28 . 29 arranged. The discharge switch 28 . 29 close in a switching state the respective discharge current path 25 . 26 and open it in another switching state.

The discharge switch 28 . 29 are each with a circuit breaker 19 . 20 via a mechanical coupling 30 . 31 connected such that an opening of the respective circuit breaker 19 . 20 inevitably closing the associated discharge switch 28 . 29 causes.

This ensures that the vehicle condition signal 18 not just the circuit breakers 19 . 20 be opened, but that simultaneously with the opening the discharge switch 28 . 29 getting closed.

In the discharge current paths 25 . 26 is an electrical consumer 32 arranged.

With closed discharge switches 28 respectively. 29 becomes the DC link capacitor 14 over this electrical consumer 32 discharged.

At the in 2 embodiment shown is the electrical load 32 in both discharge paths 25 . 26 provided jointly. These are the discharge switch 28 . 29 arranged parallel to each other and the discharge current paths 25 . 26 otherwise formed as a discharge current path.

Out 2 it can be seen that already opening a single circuit breaker 19 . 20 is enough to then the supply unit 8th separate DC link capacitor 14 over the electrical consumer 32 to unload.

This is due to the parallel connection of the discharge switch 28 . 29 reached.

The electrical consumer 32 can be used as a PTC resistor 33 be educated.

At the in 2 only symbolically shown electrical consumers 32 However, it can also be the first power section 10 for starter current and / or for the second power section 11 act for rotor excitation. Here, the rotor energization takes place such that only the d-axis of the rotor is energized and therefore no torque is formed even when energized stator.

The electrical consumer 32 can also be done by the DC / DC controller 34 be given, which is the low-voltage battery 35 from the high voltage intermediate circuit 9 with low voltage and below 50 V, for example 12 V or 6 V, feeds. This low voltage battery 35 is to a not shown, known per se low-voltage circuit of the electric vehicle 1 connected.

In other embodiments, it is provided that the described electrical consumers or other electrical consumers as needed in the discharge current path 25 . 26 be coupled.

The method according to the invention therefore provides, as a function of the vehicle condition signal 18 the supply unit 8th galvanic from the high voltage intermediate circuit 9 disconnect, so that the supply of the electric motor 7 is interrupted. With the separation of the supply unit 8th At the same time, at least one discharge current path is generated 25 . 26 closed, causing the DC link capacitor 14 over the electrical consumer 32 unloaded. The simultaneous closing is done by the mechanical coupling 30 . 31 achieved, so that the closure of the discharge current paths 2 . 26 by the separation of the supply unit 8th is effected.

Instead of the mechanical coupling 30 . 31 An optical coupling or an electrical coupling can also be used.

The invention accordingly relates to a device for producing a safe operating state in an electric vehicle 1 in which the electric vehicle has at least one electric motor 7 to its drive, which via a high voltage intermediate circuit 9 from a supply unit 8th is powered, with a circuit breaker 19 . 20 with which the supply unit 8th from the high voltage intermediate circuit 9 is galvanically separable, is provided and wherein a DC link capacitor 14 of the high voltage intermediate circuit 9 at least one discharge current path 25 . 26 is formed, via which the intermediate circuit capacitor 14 by means of a circuit breaker 19 . 20 separate supply unit 8th is dischargeable.

Claims (10)

Device for producing a safe operating state of a high-voltage intermediate circuit ( 9 ) of an electric vehicle ( 1 ), wherein the high voltage intermediate circuit ( 9 ) from a supply unit ( 8th ) and the high voltage intermediate circuit ( 9 ) a DC link capacitor ( 14 ), which has an electric motor ( 7 ), whereby two circuit breakers ( 19 . 20 ) are provided, and wherein each terminal pole ( 15 . 16 ) of the supply unit ( 8th ) by a respective disconnector ( 19 . 20 ) from the high voltage intermediate circuit ( 9 ) is separable, and wherein two additional discharge current paths ( 25 . 26 ) between the connecting poles ( 23 . 24 ) of the DC link capacitor ( 14 ) are formed, each of which individually for discharging the DC link capacitor ( 14 ) with separate disconnector ( 19 . 20 ) and wherein in each additional discharge current path ( 25 . 26 ) each have a separate discharge switch ( 28 . 29 ), which alone has the discharge current path ( 25 . 26 ), the discharge switches ( 28 . 29 ) are arranged in parallel and each of these separate discharge switch ( 28 . 29 ) one of the disconnectors ( 19 . 20 ), each discharge switch ( 28 . 29 ) with the associated disconnector ( 19 . 20 ) is coupled such that opening the circuit breaker ( 19 . 20 ) closing the respective discharge current path ( 25 . 26 ) via the associated discharge switch ( 28 . 29 ), wherein the coupling between disconnect switch ( 19 . 20 ) and associated discharge switch ( 28 . 29 ) is mechanically formed, wherein a triggering device ( 17 ) is provided, which in dependence on a vehicle condition signal ( 18 ) the circuit breakers ( 19 . 20 ). Device according to one of the preceding claims, characterized in that in the discharge current path ( 25 . 26 ) an electrical consumer ( 32 ) is arranged. Device according to one of the preceding claims, characterized in that the electrical consumer ( 32 ) an ohmic resistor, in particular a PTC thermistor or resistor ( 33 ), and / or that the electrical consumer ( 32 ) a rotor excitation of the electric motor ( 7 ), in particular for reactive current injection of a rotor of the electric motor ( 7 ) is set up. Device according to one of the preceding claims, characterized in that the electrical consumer ( 32 ) a stator current supply of the electric motor ( 7 ) and / or that the electrical consumer ( 32 ) a DC / DC controller ( 34 ) between the high voltage intermediate circuit ( 9 ) and a low voltage circuit. Device according to one of the preceding claims, characterized in that in each discharge current path ( 25 . 26 ) exactly one discharge switch ( 28 . 29 ) is arranged. Device according to one of the preceding claims, characterized in that the at least one disconnecting switch ( 19 . 20 ) and / or the discharge switch ( 28 . 29 ) in spatial proximity to the supply unit ( 8th ) is / are arranged. Device according to one of the preceding claims, characterized in that the supply unit ( 8th ) is a high voltage battery. Device according to one of the preceding claims, characterized in that a sensor for detecting a vehicle state is formed, wherein a vehicle condition dependent vehicle condition signal ( 18 ) of the sensor the at least one disconnect switch ( 19 . 20 ). Electric vehicle ( 1 ), wherein a high voltage intermediate circuit ( 9 ) from a supply unit ( 8th ) and the high voltage intermediate circuit ( 9 ) a DC link capacitor ( 14 ), which has an electric motor ( 7 ), characterized in that a device according to one of the preceding claims is included. Method for producing a safe operating state of a high-voltage intermediate circuit ( 9 ) of an electric vehicle ( 1 ), wherein in dependence on a vehicle condition signal ( 18 ) via a triggering device ( 17 ) a supply unit ( 8th ) of an electric motor ( 7 ) supplying high voltage intermediate circuit ( 9 ) from the high voltage intermediate circuit ( 9 ) is electrically isolated, each pole ( 15 . 16 ) of the supply unit ( 8th ) by a separate disconnect switch ( 19 . 29 ) from the high voltage intermediate circuit ( 9 ) and after galvanic isolation a DC link capacitor ( 14 ) of the high-voltage intermediate circuit ( 9 ) via two additional discharge current paths ( 25 . 26 ) between the connecting poles ( 23 . 24 ) of the DC link capacitor ( 14 ), wherein in each discharge current path ( 25 . 26 ) a separate discharge switch ( 28 . 29 ) is arranged and the discharge switch ( 28 . 29 ) are arranged in parallel, and each discharge switch ( 28 . 29 ) alone the additional discharge path ( 25 . 26 ), wherein opening the respective circuit breaker ( 28 . 29 ) via a mechanical coupling ( 30 . 31 ) inevitably closing the disconnect switch ( 28 . 29 ) associated discharge switch ( 28 . 29 ), each discharge current path ( 25 . 26 ) by the separation of the supply unit ( 8th ) through the circuit breaker ( 19 . 20 ) is closed.

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