DE102010030693A1 - Circuit arrangement for e.g. motor car, has switching element coupled to connection unit and pre-charge circuit in switch positions, where pre-charge circuit is provided with ohmic resistor and inductor that are connected in series - Google Patents

Abstract

The arrangement (10) has an energy storage (200) provided with two connection parts (A1, A2), and a series connection part provided with a pre-charge switching element (S V) and a pre-charge circuit (300). The series connection part is arranged parallel to a main switch (S H1), and the pre-charge switching element is electrically coupled to one of the connection parts of the energy storage and the pre-charge circuit in switch positions. The pre-charge circuit is provided with an ohmic resistor (R V) and an inductor (L V) that are connected in series. Independent claims are also included for the following: (1) a method for operating a circuit arrangement for a motor car (2) a device for operating a circuit arrangement for a motor car, comprising a pre-charge switching element.

Description

The invention relates to a circuit arrangement for a motor vehicle and to a method and a device for operating the circuit arrangement.

Battery and fuel cell motor vehicles and hybrid vehicles have an electrical energy storage that provides the electrical power for an electric drive. A DC voltage of the energy storage is converted, for example by means of a power converter in a multi-phase AC voltage, which is an electric motor which drives the motor vehicle, is supplied.

US Pat. No. 5,619,076 discloses a circuit arrangement for coupling and decoupling a battery and an uninterruptible power supply. The circuit arrangement comprises a battery, a DC bus, a main switch, an auxiliary switch and a precharge resistor. The pre-charging resistor is designed as a PTC thermistor in order to limit the current flow in the event of a fault.

EP 1 024 574 B1 discloses a circuit arrangement in which at least one primary winding of a transformer via a circuit breaker with an AC voltage network is connectable and a pulse converter is connectable to at least one secondary winding of the transformer. A precharging device is connected to an intermediate circuit of the pulse converter, the precharging device having a DC / DC converter or a matching transformer and a diode bridge.

The object on which the invention is based is to provide a circuit arrangement for a motor vehicle and a method and a device for operating the circuit arrangement, which enable a reliable and safe operation of the motor vehicle.

The object is solved by the features of the independent claims. Advantageous embodiments of the invention are characterized in the subclaims.

The invention is characterized according to a first aspect by a circuit arrangement for a motor vehicle. The circuit arrangement comprises a power converter, which has a first input terminal and a second input terminal, and at least one DC link capacitor, which capacitively couples the first input terminal and the second input terminal of the power converter. Furthermore, the circuit arrangement comprises an energy store having a first terminal and a second terminal, and a first main switch which electrically couples the first input terminal of the power converter and the first terminal of the energy store in a first switching position and makes a contribution in a second switching position Connection of the energy storage device to decouple from the first input terminal of the power converter. Furthermore, the circuit arrangement comprises a series connection with a precharge switching element and a precharge circuit, wherein the series connection is arranged parallel to the first main switch and the precharge switching element electrically couples the first connection of the energy accumulator and the precharge circuit in a first switching position and decouples them in a second switching position. The precharge circuit has at least one ohmic resistance and an inductance, which are connected in series.

This has the advantage that the energy storage device can be electrically decoupled from the intermediate circuit capacitor when needed, for example at the beginning of a rest phase of the motor vehicle, and can be electrically coupled to the intermediate circuit capacitor at the end of a rest phase. The energy store can have a positive pole and a negative pole. The energy storage, which can be used for example in electric and hybrid vehicles, may have an energy storage voltage in the range of several hundred volts. The DC link capacitor can be used to keep an input voltage of the power converter approximately constant. The DC link capacitor may have a capacitance in the range of several microfarads when used in conjunction with such an energy store of an electric or hybrid vehicle. For safety reasons, it can therefore be provided that, in particular in a rest phase of the motor vehicle, the positive pole and / or the negative pole of the energy store are electrically decoupled from the DC link capacitor. When starting the motor vehicle, the Vorladeschaltelement and the Vorladeschaltung can be used to pre-charge the DC link capacitor before closing the first main switch takes place. A pre-charging of the intermediate circuit capacitor has the advantage that when closing the first main switch a limited current flows, provided that the second terminal of the energy storage and the second input terminal of the power converter are electrically coupled to a same reference potential and / or for example a second main switch electrically couples the second terminal of the energy store with the second input terminal of the power converter. In comparison, when the DC link capacitor is not pre-charged and the first main switch is controlled to the second switching position, a short-circuit current can flow, which causes damage to the energy store and / or the Intermediate circuit capacitor and / or other switching elements can cause.

The precharging of the intermediate circuit capacitor can advantageously take place via the precharge circuit. The ohmic resistance and the inductance form a damped resonant circuit with the DC link capacitor. The pre-charging of the capacitor via the ohmic resistance and the inductance has the advantage over a current limit by means of a pure ohmic resistor that the intermediate circuit capacitor can be charged to a desired voltage, which may be greater than an output voltage of the energy storage. This allows, for example in finite time equality of the output voltage of the energy storage and the voltage of the DC link capacitor cause, so that, for example, when closing the first Hauptschlaters no or only a very small compensation current between the energy storage and the DC link capacitor can flow. A dimensioning of the ohmic resistance and / or the inductance can be dimensioned depending on a desired rise time and / or a maximum overshoot of a capacitor voltage applied to the intermediate circuit capacitor.

According to an advantageous embodiment, the precharge circuit has a freewheeling diode and the freewheeling diode is arranged parallel to the ohmic resistance and the inductance such that an anode of the freewheeling diode is electrically coupled to the first input terminal of the power converter. The diode in parallel with the resistor and the inductor becomes conductive when the capacitor voltage of the intermediate circuit capacitor exceeds the output voltage of the energy store by a threshold voltage of the freewheeling diode. As a result, a contribution can be made to prevent an overshoot of the intermediate circuit voltage beyond the output voltage of the energy store and thus to simplify a control of the first main switch.

According to an advantageous embodiment, the precharge circuit to the freewheeling diode and the freewheeling diode is arranged parallel to the inductance such that the anode of the freewheeling diode is electrically coupled to the first input terminal of the power converter. This has the advantage that the capacitor approaches the intermediate circuit capacitor to the output voltage of the energy storage. A dimensioning of the ohmic resistance and / or the inductance can be dimensioned depending on a desired rise time. Advantageously, it is thus possible to keep the desired rise time small in comparison to an arrangement with only one precharge resistor.

The invention is characterized according to a second and third aspect by a method and a corresponding device for operating a circuit arrangement for a motor vehicle according to the first aspect. At the beginning of a rest phase of the motor vehicle, the first main switch and the Vorladeschaltelement are controlled in the second switching position. At the end of a rest phase of the motor vehicle Vorladeschaltelement is controlled in the first switching position. Furthermore, a capacitor voltage is detected. If it is detected that the capacitor voltage is equal to a predetermined desired voltage value, the first main switch is controlled in the first switching position and the Vorladeschaltelement in the second switching position.

Embodiments of the invention are explained in more detail below with reference to the schematic drawings. Show it:

1 a first embodiment of a circuit arrangement 10 for a motor vehicle,

2 A second embodiment of the circuit arrangement 10 for a motor vehicle.

3 a first course of a capacitor voltage U_C,

4 a second course of the capacitor voltage U_C and
Elements of the same construction or function are provided across the figures with the same reference numerals.

The circuit arrangement 10 in 1 includes an energy store 200 with a first terminal A1 and a second terminal A2. The energy storage 200 For example, it can be used in an electric or hybrid motor vehicle and be designed to provide an electrical power for an electric drive of the motor vehicle. The energy storage 200 For example, it may have an output voltage U_Batt of several hundred volts.

Furthermore, the circuit arrangement comprises 10 a power converter 100 which has a first input terminal E1 and a second input terminal E2. The power converter 100 may be formed, for example, a DC voltage of the energy storage 200 to convert into a multi-phase AC voltage, which is supplied to an electric motor which drives the motor vehicle.

The circuit arrangement 10 comprises at least one intermediate circuit capacitor C_ZK, the first input terminal E1 and the second input terminal E2 of the power converter 100 capacitive coupled. The DC link capacitor C_ZK, for example, has a capacity of several microfarads and is used to an input voltage of the power converter 100 , which is present between the first input terminal E1 and the second input terminal E2, to keep as constant as possible.

The circuit arrangement 10 has, for example, a first main switch S_H1, which in a first switching position the first input terminal E1 of the power converter 100 and the first terminal A1 of the energy storage 200 electrically coupled and in a second switching position makes a contribution to the first port A1 of the energy storage 200 from the first input terminal E1 of the power converter 100 to decouple. The first main switch S_H1 can be designed, for example, as an estimation switch, isolator or relay.

Furthermore, the circuit arrangement 10 For example, a second main switch S_H2, in a first switching position, the second input terminal E2 of the power converter 100 and second terminal A2 of the energy storage 200 electrically coupled and electrically decoupled in the second switching position. This allows, in particular in a rest phase of the motor vehicle, a positive pole and / or a negative pole of the energy store 200 can be electrically decoupled from the DC link capacitor C_ZK.

Furthermore, the circuit arrangement comprises 10 a series circuit including a precharge switching element S_V and a precharge circuit 300 , wherein the series circuit is arranged parallel to the first main switch S_H1 and the Vorladeschaltelement S_V in a first switching position, the first terminal A1 of the energy storage 200 and the precharge circuit 300 electrically coupled and decoupled in a second switching position. The precharge circuit 300 has, for example, an ohmic resistor R_V and an inductance L_V, which are connected in series.

2 shows a further embodiment of the circuit arrangement 10 , Compared to the in 1 shown embodiment, the Vorladeschaltung 300 a freewheeling diode D, which is so arranged in parallel to the ohmic resistor R_V and the inductance L_V, that an anode AN of the freewheeling diode D is electrically coupled to the first input terminal E1 of the power converter 100 ,

A program for operating the circuitry 10 of the motor vehicle can be stored, for example, in a program memory of a control unit, such as a control unit. The control unit is designed, for example, to execute the program. The control unit can also be used as a device for operating the circuit arrangement 10 be designated.

The program can be started, for example, in a step S1. In a step S2, it is detected, for example, whether the motor vehicle has a first operating state or a second operating state, wherein the first operating state represents a start of a rest phase of the motor vehicle and the second operating state represents an end of a rest phase of the motor vehicle.

If it is detected in step S2 that the vehicle has the first operating state, in a step S3 the first main switch S_H1 and the precharge switching element S_V are controlled to the second switching position, ie opened. Indicates the circuitry 10 Also, the second main switch S_H2, preferably also the second main switch S_H2 is controlled in the second switching position, ie opened.

If it is detected in step S2 that the motor vehicle has the second operating state, in a step S4 the precharge switching element S_V is controlled to the first switching position and in a step S6 a capacitor voltage U_C is detected. If it is detected in a step S8 that the capacitor voltage U_C is equal to a predefined setpoint voltage value U_setpoint, the setpoint voltage value U_setpoint preferably being an output voltage U_Batt of the energy store 200 represents, in a step S10, the first main switch S_H1 is controlled in the first switching position, ie closed, and the Vorladeschaltelement S_V controlled in the second switching position, ie opened.

3 shows a profile of the capacitor voltage U_C for an embodiment in which the Vorladeschaltung 300 has only one ohmic resistance R_V. When closing the Vorladeschaltelements S_V and the second main switch S_H2 flows in a circuit arrangement 10 according to 1 or 2 a stream from the energy store 200 to the DC link capacitor C_ZK. The current is limited by the ohmic resistance R_V. The capacitor voltage U_C of the DC link capacitor C_ZK increases. The course of the capacitor voltage U_C represents approximately an expotential function. The capacitor voltage U_C approaches the output voltage U_Batt of the energy store 200 at. For example, it may be provided that when a difference between the output voltage U_Batt of the energy storage 200 and the capacitor voltage U_C falls below a predetermined threshold value, the first main switch S_H1 is closed and the precharge switching element S_V is opened. Since the capacitor voltage U_C can not rise when the first main switch S_H1 is open, until the output voltage U_Batt of the energy storage 200 is reached, flows when closing the first main switch S_H1 in this case for a short period of time, a high current in the DC link capacitor C_ZK, which can cause damage and / or accelerated aging. A rise time until the difference between the output voltage U_Batt of the energy storage 200 and the capacitor voltage U_C falls below a predetermined threshold, for example, depends on a dimensioning of the ohmic resistance R_V.

4 on the other hand shows the course of the capacitor voltage in the event that the Vorladeschaltung 300 , as in 1 and 2 shown having inductance L_V. After closing the precharge switching element S_V, the capacitor voltage U_C increases. The inductance L_V first drives the current further. Advantageously, the first main switch S_H1 is closed at a time t_o when the capacitor voltage U_C the output voltage U_Batt of the energy storage 200 has reached about as in this case as well as no compensation current from the energy storage 200 flows to the DC link capacitor C_ZK. If the first main switch S_H1 is not closed at the time t_o, the capacitor voltage U_C may be a damped oscillation around the output voltage U_Batt of the energy store 200 exhibit.

At the in 2 In the embodiment shown, the diode D becomes conductive in parallel to the resistor R_V and the inductance L_V, for example, when the capacitor voltage U_C of the intermediate circuit capacitor C_ZK is the output voltage U_Batt of the energy store 200 exceeds. This can overshoot the capacitor voltage U_C via the output voltage U_Batt of the energy store 200 Be prevented.

LIST OF REFERENCE NUMBERS

10

Circuit arrangement for a motor vehicle

100

power converters

200

energy storage

300

precharge circuit

A1

first connection of the energy storage

A2

second connection of the energy storage

AT

anode

C_ZK

Link capacitor

D

Freewheeling diode

E1

first input terminal of the power converter

E2

second input connection of the converter

L_V

inductance

R_V

ohmic resistance

S_H1

first main switch

S_H2

second main switch

S_V

Vorladeschaltelement

T_O

time

u_Batt

Output voltage of the energy storage

U_C

capacitor voltage

U_Soll

Target voltage value

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5619076 [0003]
• EP 1024574 B1 [0004]

Claims (5)

Circuit arrangement ( 10 ) for a motor vehicle, comprising: - a power converter ( 100 ) having a first input terminal (E1) and a second input terminal (E2), - at least one DC link capacitor (C_ZK), the first input terminal (E1) and the second input terminal (E2) of the power converter ( 100 ) capacitively coupled, - an energy store ( 200 ) with a first connection (A1) and a second connection (A2), - a first main switch (S_H1), which in a first switching position the first input connection (E1) of the power converter ( 100 ) and the first terminal (A1) of the energy store ( 200 ) electrically coupled and in a second switching position makes a contribution, the first terminal (A1) of the energy store ( 200 ) from the first input terminal (E1) of the power converter ( 100 ), and - a series connection with a precharge switching element (S_V) and a precharge circuit ( 300 ), wherein - the series connection is arranged parallel to the first main switch (S_H1), - the Vorladeschaltelement (S_V) in a first switching position the first terminal (A1) of the energy storage ( 200 ) and the precharge circuit ( 300 ) electrically coupled and electrically decoupled in a second switching position, and - the precharge circuit ( 300 ) has at least one ohmic resistance (R_V) and an inductance (L_V) connected in series. Circuit arrangement ( 10 ) according to claim 1, wherein the precharge circuit ( 300 ) has a free-wheeling diode (D) and the free-wheeling diode (D) is arranged parallel to the ohmic resistor (R_V) and the inductance (L_V) such that an anode (AN) of the freewheeling diode (D) is electrically coupled to the first input terminal ( E1) of the power converter ( 100 ). Circuit arrangement ( 10 ) according to claim 1, wherein the precharge circuit ( 300 ) has the freewheeling diode (D) and the freewheeling diode (D) is arranged parallel to the inductance (L_V) such that the anode (AN) of the freewheeling diode (D) is electrically coupled to the first input terminal (E1) of the power converter ( 100 ). Method for operating a circuit arrangement ( 10 ) for a motor vehicle according to one of claims 1 to 3, wherein at the beginning of a rest phase of the motor vehicle, the first main switch (S_H1) and the Vorladeschaltelement (S_V) are controlled in the second switching position, and at the end of a rest phase of the motor vehicle - the Vorladeschaltelement ( S_V) are controlled in the first switching position, - a capacitor voltage (U_C) is detected, and - if it is detected that the capacitor voltage (U_C) is equal to a predetermined desired voltage value (U_soll), the first main switch (S_H1) in the first Controlled switching position and the Vorladeschaltelement (S_V) is controlled in the second switching position. Device for operating a circuit arrangement ( 10 ) for a motor vehicle according to one of claims 1 to 3, which is designed, at the beginning of a rest phase of the motor vehicle to control the first main switch (S_H1) and the Vorladeschaltelement (S_V) in the second switching position, and at the end of a rest phase of the motor vehicle - To control a Vorladeschaltelement (S_V) in the first switching position, - to detect a capacitor voltage (U_C), and - if it is detected that the capacitor voltage (U_C) is equal to a predetermined desired voltage value (U_soll), the first main switch (S_H1) in to control the first switching position and to control the Vorladeschaltelement (S_V) in the second switching position.

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