DE102017209105A1 - Device and method for discharging a high-voltage DC link of a vehicle - Google Patents

Abstract

Device (10) for discharging a high-voltage intermediate circuit (20) of a vehicle. The high-voltage intermediate circuit (20) comprises an intermediate circuit capacitor (30) and a step-down converter (40), which converts a high-voltage (U_H) of the high-voltage intermediate circuit (20) into a low-voltage (U_L). The device (10) comprises a low-voltage discharge circuit (50) which is connected to the buck converter (40) on the low-voltage side. Further, the device (10) comprises means (60) which are adapted to turn on the low-voltage discharge circuit (50) in response to a discharge signal (SIG).

Description

The invention relates to a device and a method for discharging a high-voltage intermediate circuit of a vehicle. Furthermore, the invention relates to a drive train with a corresponding device and a vehicle with a drive train, as well as a computer program and a machine-readable storage medium.

State of the art

From the WO 2009/106187 A1 a method and apparatus for discharging a high voltage network is known. In conventional vehicles, the voltage in the electrical system is about 14 volts. In hybrid vehicles or vehicles with electric drive voltages in the traction network are used, which can be several 100 volts. Electrical voltages greater than 60 volts are referred to as high voltage. For reasons of safety, high-voltage networks, in particular electrical systems or traction networks, must be able to be switched off and discharged. Known high-voltage networks include for this purpose an active discharge device. This device usually consists of a two-pole main switch for disconnecting the battery from the rest of the network and a switchable resistor, via which the charge is reduced if necessary. Alternatively, a passive discharge device can also be used. As a rule, this device consists of at least one resistor which is connected in parallel to the energy store and to the high-voltage network. Such passive discharge circuits are set up to discharge a DC link capacitor located in the high-voltage network, in particular a so-called DC link capacitor, to a voltage of less than 60 volts (contact safety) within a predetermined time, usually 120 seconds, independently of an initially occurring voltage. There is a need to provide alternative discharge methods and devices for high voltage automotive networks.

Disclosure of the invention

An apparatus for discharging a high-voltage DC link of a vehicle is provided. The high-voltage intermediate circuit comprises an intermediate circuit capacitor and a step-down converter, which converts a high-voltage voltage of the high-voltage intermediate circuit into a low-voltage voltage. The device comprises a low-voltage discharge circuit, which is electrically connected on the low-voltage side with the buck converter. Furthermore, the device comprises means which are adapted to turn on the low-voltage discharge circuit in response to a discharge signal.

A device is provided which is suitable for discharging a high-voltage intermediate circuit of a vehicle. The high-voltage intermediate circuit comprises an intermediate circuit capacitor, which is connected, for example, for the operation of an electrical machine high-voltage side between a pulse inverter and a high-voltage battery for smoothing the resulting during operation of the pulse inverter current and voltage peaks. Furthermore, the high-voltage intermediate circuit comprises a buck converter. A buck converter is set up to convert a higher DC voltage into a lower DC voltage. As a step-down converter, for example, a DCDC converter, a Flyback converter, or a flyback converter, or a forward converter can be used. The step-down converter converts the high-voltage voltage present in the high-voltage intermediate circuit into a low-voltage voltage. The device comprises a low-voltage discharge circuit. The low-voltage discharge circuit is used for discharging the high-voltage intermediate circuit. For this purpose, the low-voltage discharge circuit is electrically connected via the buck converter with the high-voltage intermediate circuit. For this purpose, the output terminals of the buck converter are electrically connected to the input terminals of the low-voltage discharge circuit. The low-voltage discharge circuit is designed for operation with the low-voltage, which outputs the buck converter low-voltage side. The low-voltage discharge circuit is turned on in response to a charging signal. For this purpose, the device comprises a means arranged for this purpose. Advantageously, a device for discharging a high-voltage intermediate circuit is provided, which is designed for a defined low-voltage. Due to the lower electrical voltage of the low-voltage discharge circuit results in a simplified circuit structure compared to a high-voltage discharge circuit and associated cost and space advantages.

In another embodiment of the invention, the low-voltage discharge circuit is adapted to adjust the height of the discharge current as a function of the low-voltage.

The low-voltage discharge circuit is designed such that the height of the discharge current in dependence on the low-voltage, which outputs the buck converter low voltage side, is set. A hardware circuit may be configured such that the magnitude of the discharge current changes depending on the low-voltage voltage. For this purpose, the hardware circuit can comprise, for example, a potential divider composed of a resistor series circuit, to the center tap of which, in particular, the gate of a transistor for switching the discharge current is connected. The height of the discharge current can alternatively by means of a logic unit, such as a microcontroller, in Dependence of a measured low-voltage can be adjusted. Advantageously, a device for discharging is provided in which an overload of the buck converter is avoided.

In another embodiment of the invention, the discharge current is blocked by the low-voltage discharge circuit, if the low-voltage is less than a lower operating voltage value.

When the low-voltage voltage decreases to a value lower than a lower operating voltage value, the discharge current is blocked by the low-voltage voltage or prevented from flowing of the discharge current by the low-voltage discharge circuit. For example, the fact that the circuit is interrupted by the low-voltage discharge circuit or passed through a very high resistance. Advantageously, a device for discharging a high-voltage DC link is provided via a step-down converter, in which the step-down converter is not overloaded.

In another embodiment of the invention, the discharge current through the low-voltage discharge circuit is a maximum, if the low-voltage is greater than an upper operating voltage value.

If the low-voltage is greater than an upper operating voltage value, the low-voltage discharge circuit is in particular switched through. Consequently, the maximum discharge current flows through the low-voltage discharge circuit. For example, for this purpose, the circuit is closed by the low-voltage discharge circuit and in particular minimizes the resulting within the circuit of the low-voltage discharge circuit resistance. Advantageously, a device for discharging a high-voltage intermediate circuit is provided, which allows the removal of the maximum power from the high-voltage intermediate circuit as long as the buck converter is not overloaded.

In another embodiment of the invention, the discharge current is linearly controlled by the low-voltage discharge circuit, if the low-voltage is less than the upper operating voltage value and greater than the lower operating voltage value. If the low-voltage is in a range between the lower operating voltage value and the upper operating voltage value, the discharge current is linearly controlled by the low-voltage discharge circuit. In particular, for this purpose, the transistor used to control the discharge current is operated in the linear range. At higher low voltage results in a higher load current and at lower low voltage results in a lower discharge current through the low-voltage discharge circuit. For example, this regulation is effected by means of a MOSFET, at whose gate a voltage is applied, which is designed in proportion to the low-voltage. Advantageously, a device for discharging a high-voltage intermediate circuit is provided, which can be discharged with the maximum power of the buck converter.

In another embodiment of the invention, the low-voltage discharge circuit as a consumer comprises a semiconductor switch, transistor or MOSFET.

The load required for the discharge of a high-voltage intermediate circuit is designed, for example, as a semiconductor switch, transistor or MOSFET and a component of the low-voltage discharge circuit. Advantageously, variants are provided for a consumer of the low-voltage discharge circuit.

Furthermore, the invention relates to a drive train with a device and in particular a power electronics and / or a high-voltage battery and / or an electric drive.

Such a drive train is used, for example, the drive of an electric vehicle. By means of the method and the device, a safe operation of the drive train is made possible, in particular a safe active discharge of the high-voltage intermediate circuit of the drive train possible.

Furthermore, the invention relates to a vehicle with a described device. Advantageously, a vehicle is thus provided which comprises a device with which an efficient discharge of a high-voltage intermediate circuit takes place.

Furthermore, the invention relates to a method for discharging a high-voltage DC link of a vehicle. The high-voltage intermediate circuit comprises an intermediate circuit capacitor and a step-down converter, which converts a high-voltage voltage of the high-voltage intermediate circuit into a low-voltage voltage. There is provided a low-voltage discharge circuit, which is electrically connected to the low-set side with the buck converter. The method comprises the steps of turning on the low-voltage discharge circuit in response to a discharge signal; Determining the low-voltage voltage; Adjustment of the discharge current through the low-voltage discharge circuit as a function of the determined low-voltage.

A method is provided which is suitable for discharging a high-voltage intermediate circuit of a vehicle. The high-voltage intermediate circuit comprises an intermediate circuit capacitor, which, for example, for the operation of an electrical machine high-voltage side between a pulse inverter and a high-voltage battery for smoothing the Current and voltage peaks is switched. Furthermore, the high-voltage intermediate circuit comprises a buck converter. The step-down converter converts the high-voltage voltage present in the high-voltage intermediate circuit into a low-voltage voltage. For the discharge of the high-voltage intermediate circuit, a low-voltage discharge circuit is used. For this purpose, the low-voltage discharge circuit is electrically connected via the buck converter with the high-voltage intermediate circuit. By means of a method step, the low-voltage discharge circuit is turned on in response to a charging signal. Next, the low-voltage is determined. This takes place for example by means of known measuring methods or by means of a hardware circuit. Depending on the determined low-voltage voltage, the discharge current is adjusted by the low-voltage discharge circuit. Advantageously, a method for discharging a high-voltage intermediate circuit is provided.

Furthermore, the invention relates to a computer program that is configured to carry out the method described so far.

Furthermore, the invention relates to a machine-readable storage medium on which the computer program described is stored.

It is understood that the features, properties and advantages of the device according to the invention corresponding to the method or the drive train and the vehicle and vice versa apply or are applicable.

Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings.

list of figures

• 1 zeigt eine schematische Darstellung einer Vorrichtung zur Entladung eines Hochvolt-Zwischenkreises des Fahrzeugs,
• 2 eine schematische Darstellung eines Antriebsstrangs mit einer Vorrichtung,
• 3 ein schematisch dargestelltes Fahrzeug mit einem Antriebsstrang,
• 4 ein schematisch dargestelltes Ablaufdiagramm für ein Verfahren zur Entladung eines Hochvolt-Zwischenkreises eines Fahrzeugs,
• 5 eine schematische Darstellung einer Niedervolt-Entladeschaltung.

In the following, the invention will be explained in more detail with reference to some figures, in which:

• 1 shows a schematic representation of a device for discharging a high-voltage intermediate circuit of the vehicle,
• 2 a schematic representation of a drive train with a device,
• 3 a schematically illustrated vehicle with a drive train,
• 4 a schematically illustrated flowchart for a method for discharging a high-voltage DC link of a vehicle,
• 5 a schematic representation of a low-voltage discharge circuit.

Embodiments of the invention

The 1 shows a high-voltage intermediate circuit 20 to which a high-voltage voltage U_H is applied. The high-voltage DC link comprises a DC link capacitor 30 and a buck converter 40 , Low voltage side is located on the buck converter 40 the low-voltage U_L on. Low voltage side is the device 10 for discharging a high-voltage intermediate circuit to the buck converter 40 electrically connected. The device 10 for discharging a high-voltage intermediate circuit comprises a low-voltage discharge circuit 50 with a consumer 70 , which consumes the electrical energy from the high-voltage intermediate circuit for discharging the high-voltage intermediate circuit, for example, converted into heat. In this case, the discharge current I_D flows through the low-voltage discharge circuit 50 , Furthermore, the device comprises 10 a means 60 which is adapted to receive a discharge signal SIG. Next is the remedy 60 to set up depending on the signal SIG, the low-voltage discharge circuit 50 turn on, in particular a current flow from the buck converter 40 in the discharge circuit 50 to enable, for example, by closing a switch (not shown) in the electrical connection between the buck converter 40 and the discharge circuit 50 , With this arrangement, a device 10 provided for discharging a high-voltage intermediate circuit.

The 2 shows an electric drive train 100 with a device 10 for discharging the high-voltage intermediate circuit 20 which by means of a buck converter 40 with the device 10 is coupled. The high-voltage DC link 20 includes a DC link capacitor 30 , In particular, the electric drive train includes 100 a battery 80 and / or a pulse inverter 90 , the Indian 2 is shown as a B6 bridge, and / or an electric machine 95 , In particular for feeding the electric machine 95 is the high-voltage DC link 20 in particular by means of a pulse inverter 90 which couples the electrical energy from the battery 80 to the electric machine 95 or vice versa.

3 shows a schematically illustrated vehicle 200 with a powertrain 100 , which is used to drive the vehicle 200 is set up to at least one wheel 210 of the vehicle. The illustration shows an example of a vehicle 200 with four wheels 210 , wherein the invention equally usable in any vehicles with any number of wheels on land to water and in the air.

The 4 shows a schematic sequence of a method 300 for discharging a high-voltage DC link 20 of a vehicle. With step 310 the procedure begins. In step 320 becomes the low-voltage discharge circuit 50 activated as a function of a discharge signal SIG. The low voltage U_L at the entrance of the low-voltage discharge circuit 50 will be in step 330 determined. Depending on the determined low-voltage U_L becomes the discharge current I_D through the low-voltage discharge circuit 50 in step 340 set. With step 350 the procedure ends.

5 shows an example of a device 10 comprising a low-voltage discharge circuit 50 and means 60 which are adapted to the low-voltage discharge circuit 50 to turn on in response to the discharge signal SIG. By way of example, the low-voltage discharge circuit comprises a first MOSFET 70 , which as a consumer 70 the discharge circuit with the drain and source terminals to the potentials of the low voltage U_L connected. In parallel there are two resistors R1 and R2 as voltage or potential divider also to the low voltage U_L connected. An intermediate tap between the two resistors R1 and R2 is connected to the gate terminal of the first MOSFET 70 connected. At a high low voltage U_L results at the gate of the first MOSFET 70 a high voltage level, making the first mosfet 70 becomes completely conductive and a high discharge current I_D through the first MOSFET 70 flows. With decreasing voltage level of the low-voltage U_L also decreases the voltage level at the gate of the first MOSFETs 70 so that this in its linear operating range the discharge current I_D linear controls. If the voltage level of the low-voltage voltage continues to drop U_L Also, the voltage level at the gate of the first MOSFET decreases 70 so that it goes into the blocking state and the discharge current I_D is locked. Then there is no discharge and no discharge current flows I_D more. By way of example, in this embodiment, the means comprises 60 a second MOSFET S1 , In the conducting state of the second MOSFET S1 will always be the voltage level of the gate of the first MOSFET of the consumer 70 pulled to 0 volts, making the first MOSFET of the consumer 70 locks and no discharge can take place, so that the low-voltage discharge circuit 50 is switched off. If the discharge signal SIG is at a low level, for example 0 volts, the second MOSFET is located S1 in the locked state. Then is the low-voltage discharge circuit 50 switched on and actively discharges, as described, for example, one by means of a buck converter 40 connected high-voltage DC link 20 ,

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

• WO 2009/106187 A1 [0002]

Claims (11)

Device (10) for discharging a high-voltage intermediate circuit (20) of a vehicle, wherein the high-voltage intermediate circuit (20) comprises an intermediate circuit capacitor (30) and a step-down converter (40), which converts a high-voltage (U_H) of the high-voltage intermediate circuit (20) into a low-voltage (U_L); wherein the device (10) comprises a low-voltage discharge circuit (50) which is electrically connected to the buck converter (40) on the low-voltage side, and the device (10) comprises means (60) arranged to turn on the low-voltage discharge circuit (50) in response to a discharge signal (SIG). Device after Claim 1 , wherein the low-voltage discharge circuit (50) is adapted to adjust the height of the discharge current (L_D) in dependence on the low-voltage (U_L). Device after Claim 2 in that the discharge current (I_D) is blocked by the low-voltage discharge circuit (50) if the low-voltage (U_L) is less than a lower operating voltage value (U_BU). Device after Claim 3 wherein the discharge current (I_D) by the low-voltage discharge circuit (50) becomes maximum, if the low-voltage (U_L) is greater than an upper operating voltage value (U_BO). Device after Claim 4 wherein the discharge current (I_D) is linearly controlled by the low-voltage discharge circuit (50) if the low-voltage (U_L) is less than the upper operating voltage value (U_BO) and greater than the lower operating voltage value (U_BU). Device (10) according to one of the preceding claims, wherein the low-voltage discharge circuit (50) as a consumer (70) comprises a semiconductor switch, transistor or mosfet. Drive train (100) with a device (10) according to one of Claims 1 to 6 , Vehicle (200) with a drive train (100) according to Claim 7 , Method (300) for discharging a high-voltage intermediate circuit (20) of a vehicle, wherein the high-voltage intermediate circuit (20) comprises an intermediate circuit capacitor (30) and a step-down converter (40) which generates a high-voltage (U_H) of the high-voltage intermediate circuit (20) converted into a low-voltage (U_L); and a low-voltage discharge circuit (50) is provided, which is connected on the low-voltage side electrically with the step-down converter (40) with the steps: Turning on (320) the low-voltage discharge circuit (50) in response to a discharge signal (SIG); Determining (330) the low voltage voltage (U_L); Adjusting (340) the discharge current (I_D) by the low-voltage discharge circuit (50) as a function of the determined low-voltage voltage (U_L). Computer program that is set up after the method (300) Claim 9 perform. Machine-readable storage medium on which the computer program is based Claim 10 is stored.

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