DE102019002411A1 - Method Control arrangement for charging a battery of an at least partially electrically operable motor vehicle - Google Patents

Abstract

The invention relates to a method for charging a battery (1) of an at least partially electrically operable motor vehicle, the battery (1) being charged with an initial charging power (Pi), a temperature (T) of a DC link capacitor (2) of a high voltage circuit of the motor vehicle during charging is detected and the battery (1) with a relation to the initial charging power (Pi) reduced charging power (Pr) is charged when the detected temperature (T) is greater than a first limit value (T1).

Description

The invention relates to a method for charging a battery of an at least partially electrically operable motor vehicle, wherein at the beginning of a charging process, the battery is charged with an initial charging power. Furthermore, the invention relates to a corresponding control arrangement for charging a battery.

For high-voltage systems in electric vehicles, for example plug-in hybrids, battery vehicles, fuel cell vehicles and the like, for example, high-voltage batteries are charged. In this case, electrical components, in particular a DC link capacitor, may be active during a charging operation, which can lead to a heat development. Excessive heat generation can cause damage to the electrical components or the high voltage circuitry of the motor vehicle or the motor vehicle itself.

Against this background, it is an object of the present invention to provide an improved concept for charging a battery of an at least partially electrically operable motor vehicle, by means of which an increased safety during charging operation can be achieved.

According to the invention the object is achieved by a method and a control arrangement according to the independent claims. Further embodiments and advantageous embodiments are the subject of the dependent claims.

The improved concept is based on the idea of monitoring or detecting a temperature of a DC link capacitor and reducing a charging power depending on the detected temperature.

According to a first independent aspect of the improved concept, a method for charging a battery of an at least partially electrically operable motor vehicle is specified. At the beginning of a charging process, the battery is charged with an initial charging power. In particular, at the beginning of the charging process, an amount of a charging current corresponds to an initial amount of the charging current. During the charging process, a temperature of a link capacitor of a high-voltage circuit of the motor vehicle is detected. In particular, the detected temperature is compared with a first limit value. The battery is charged with a charge power reduced with respect to the initial charging power when the detected temperature is greater than the first limit value. In particular, to reduce the charging power, the amount of the charging current is reduced.

The high-voltage circuit, also called high-voltage circuit, is in particular a circuit designed for high voltages, in particular for voltages of up to 400 or up to 500 volts. In particular, "high voltage" does not necessarily mean a voltage of 1000 volts or more.

The battery is designed in particular as a high-voltage or high-voltage battery. "High voltage" can be understood analogously to the high-voltage circuit.

The high-voltage circuit may in particular be part of an electric drive train of the motor vehicle.

The electric drive train may, for example, have a motor inverter, wherein the motor inverter includes the intermediate circuit capacitor. The DC link capacitor can in particular serve to dampen voltage ripples which arise during a driving operation.

Since, for example, in an AC charging operation, voltage ripple of an AC charger can be attenuated by the DC link capacitor, the DC link capacitor is active, for example, during the charging operation.

Due to the smoothing effect, in particular during the charging process, heat is generated at the DC link capacitor or in its surroundings, in particular in the motor inverter or in the electric drive train. The heat input can be caused in particular by equalizing currents, which can follow the damping of the voltage ripple.

Excessive temperature and heat generation can damage the link capacitor or the high voltage circuit or the electric drive train.

By the method according to the improved concept, in particular by the temperature-dependent reduction of the charging power, such damage is avoided.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures are not only in the respectively indicated combination but also in other combinations or usable in isolation, without departing from the scope of the invention.

In the following, the invention will be explained in detail with reference to schematic drawings and corresponding exemplary embodiments.

• 1 ein Blockdiagramm einer Batterie und eines elektrischen Antriebsstrangs eines Kraftfahrzeugs; und
• 2 eine schematische Darstellung einer beispielhaften Ausführungsform eines Verfahrens nach dem verbesserten Konzept.

Showing:

• 1 a block diagram of a battery and an electric drive train of a motor vehicle; and
• 2 a schematic representation of an exemplary embodiment of a method according to the improved concept.

1 shows a block diagram of an electric drive train 3 and a battery 1 an electrically or partially electrically operable motor vehicle.

In particular, the motor vehicle has a control arrangement for charging the battery 1 after the improved concept. A method of charging the battery 1 according to the improved concept is in 2 shown.

Furthermore, the motor vehicle has a charger 4 on which to charge the battery 1 to a charging station 5 or can be connected to or coupled to another external charging device.

The battery 1 is with the electric drive train 3 in particular for operating the motor vehicle or an electric motor 6 of the electric drive train 3 connected. The charger 4 is for example with a connection between the battery 1 and the electric drive train 3 to charge the battery 1 connected.

During a charging process, a charging current flows I from the charger 4 to the battery 1 , In particular, the charging current has I at the beginning of the charging process an initial amount. According to a charging voltage, which is given for example, the battery 1 So loaded at the beginning of the charging process with an initial charging power.

Electrical components of the motor vehicle can also be active, for example, an electric refrigerant compressor to the battery 1 to cool.

Furthermore, for example, the electric drive train 3 , which for example a motor inverter 7 , an electric motor 6 and / or a transmission (not shown) includes being active. The electric drive train 3 , in particular the motor inverter 7 , For example, has an intermediate circuit capacitor 2 on, for example, between the battery 1 and the motor inverter 7 is arranged. During a driving operation, the DC link capacitor 2 serve to dampen the resulting voltage ripples. Such voltage ripples can by "chopping" a DC voltage in AC voltage for motor and generator operation of the electric motor 6 arise.

During the charging process, for example in an AC charging operation, can also by means of the DC link capacitor 2 a voltage ripple of the charger 4 be steamed. This may mean that an engine inverter control unit of the electric drive train 3 not necessarily "awake" during the charging process and the DC link capacitor 2 Nevertheless, resulting voltage swings in the DC voltage network smoothes.

Due to the smoothing effect can in the DC link capacitor 2 or in the motor inverter 7 Heat to be generated. The heat input can be caused by the presence of equalizing currents following the voltage damping. In fact, the DC link capacitor can 2 so heat up and thus possibly become so hot that the DC link capacitor 2 becomes conductive, whereby a hard short between positive pole of the high-voltage circuit and negative pole of the high-voltage circuit can arise. For example, the DC link capacitor 2 be formed as a film capacitor whose films can become conductive at too high heat and can generate the short circuit.

For example, in a case where the motor vehicle is loaded in an underground garage or elsewhere and the link capacitor 2 is not sufficiently cooled and thus a short circuit would be two sources, namely the charging infrastructure and the high-voltage battery 1 , Power in the DC link capacitor 2 submit. The DC link capacitor 2 would represent a conductive connection between the positive and negative poles of the high voltage circuit. The result would be an immense energy input, since only one sink but two sources would be available. Accordingly, a great deal of damage could result.

This can be prevented by the control arrangement or the method according to the improved concept.

The control arrangement has a temperature sensor which is in an environment of the intermediate circuit capacitor or on the intermediate circuit capacitor 2 is arranged to a temperature of the DC link capacitor 2 during the charging process. The temperature T For example, as a temperature signal from the temperature sensor to a controller 8th the control arrangement transmitted. The control unit 8th For example, a charging voltage U and a momentary charging power P to capture. The control unit 8th For this purpose, it can be coupled to the temperature sensor, for example by means of a CAN bus system.

The control unit 8th is set to the temperature T with a first limit T1 to compare. The comparison shows that the temperature T greater than the first limit T1 is, is the charging power P , For example, the amount of the charging current I , reduced. This will cause the temperature T decreases and overheating of the DC link capacitor 2 can be avoided.

In 2 the method is illustrated by means of a derating diagram. In this case, a maximum permissible charging power as a function of the detected temperature T shown as a line. Is the temperature T a reference temperature T0 , so a maximum charging power can be used, for example, corresponds to the initial charging power Pi of the maximum charging power. At higher temperature, especially when the temperature T greater than T1 is, the maximum allowable charging power is reduced, in particular in response to exceeding the first limit value T1 linear reduced.

In the example shown the 2 corresponds to the linear relationship between the charging power P and the temperature T a zero crossing at T = T2, where T2 represents a second limit. Exceeds the temperature T the second limit T2 , the charging process is immediately interrupted or stopped. In alternative embodiments, the second limit may also differ from a zero crossing of the linear relationship, in particular correspond to a lower temperature than the zero crossing.

According to various embodiments of the improved concept, during the charging process, the temperatures of the one or more intermediate circuit capacitors in the high-voltage system, for example of the electric drive train, are continuously queried and detected, for example, in a higher-level control unit via CAN communication. If the temperature rises above a value corresponding to the first limit value, then, for example, a linear power derating or current derating is activated, in particular, at the charger or the charging unit. The higher the temperature at the DC link capacitor 2 , the lower the charging power P or the charging current I , Should the temperature T in the DC link, the second limit T2 achieve, for example, immediately stops the charging process, so that a safe state for the motor vehicle and the high-voltage architecture is achieved. The charging current temperature monitoring function can be stored, for example, in a higher-level control unit CPC. The CPC communicates via CAN, for example, with the respective control devices, such as control units of the high-voltage battery 1 of the charger 4 and / or the electric drive train 3 , This function thus protects the vehicle, in particular the high-voltage circuit, from damage.

LIST OF REFERENCE NUMBERS

1

battery

2

Link capacitor

3

Electric drive train

4

charger

5

charging station

6

engine

7

motor inverter

8th

control unit

T

temperature

I

charging current

U

charging voltage

P

charging power

T1, T2

limits

T0

reference temperature

Claims (6)

Method for charging a battery (1) of a motor vehicle that is at least partially electrically operable, the battery (1) being charged with an initial charging power (Pi) at the beginning of a charging process, characterized in that - a temperature (T) of a DC link capacitor (2) a high voltage circuit of the motor vehicle is detected during the charging process; - The battery (1) with a relation to the initial charging power (Pi) reduced charging power (Pr) is charged when the detected temperature (T) is greater than a first limit value (T1). Method according to Claim 1 characterized in that: - an amount of the reduced charging power (Pr) depends on an amount of a difference between the detected temperature (T) and the first limit value (T1); - Where a relationship between the detected temperature (T) and the difference is particularly linear. Method according to one of Claims 1 or 2 characterized in that - the charging operation is stopped when the detected temperature (T) is greater than a second threshold (T2); - wherein the second threshold (T2) is greater than the first threshold (T1). Method according to one of Claims 1 to 3 , characterized in that the temperature (T) of the intermediate circuit capacitor (2) during the charging process several times, in particular continuously, detected and compared with the first limit value (T1). Method according to one of Claims 1 to 4 , characterized in that for charging the battery (1) with the reduced charging power (Pr) an amount of a charging current (I) compared to an initial amount of the charging current (I) is reduced. Control arrangement for charging a battery (1) of an at least partially electrically operable motor vehicle, which is adapted to a method according to one of Claims 1 to 5 and in particular comprising: a temperature sensor adapted to generate a temperature signal based on a temperature (T) of a DC link capacitor (2) of a high voltage circuit of the motor vehicle during a charging process; and - a control unit (8), which is in particular by means of a bus system, for example a CAN bus system, coupled to the temperature sensor to receive the temperature signal, configured to - based on the temperature signal, the temperature (T) with a first threshold (T1 ) to compare; and - to reduce a charging power (P) for charging the battery (1) when the temperature (T) is greater than the first limit value (T1).

Images