Method for limiting a switch-on current in an electrical system
The disclosure describes a method for limiting a switch-on current in an electrical system which is supplied with power by a battery. During a switch-on process, an electrical load is connected to the electrical system and precharged by means of a precharging resistor. A monitoring unit regularly records operating data of at least one variable which influences a temperature of the precharging resistor and estimates the temperature of the precharging resistor on the basis of said operating data. The disclosure also describes an apparatus and a battery which are designed to execute the method according to the disclosure.
1. A method for limiting a switch-on current of a circuit configured to receive current from a battery, the method comprising:
connecting an electrical load to the battery during a switch-on operation;
pre-charging the electrical load via a pre-charging resistor during the switch-on operation;
regularly recording operating data including at least one variable that influences a temperature of the pre-charging resistor with a monitoring unit;
estimating the temperature of the pre-charging resistor based on the recorded operating data;
generating a warning signal in response to the estimated temperature of the pre-charging resistor exceeding a first temperature threshold value; and
preventing pre-charging of the electrical load via the pre-charging resistor in response to the estimated temperature of the pre-charging resistor exceeding a second temperature threshold value that is greater than the first temperature threshold value.
2. The method as claimed in claim 1 , the regularly recording further comprising:
regularly recording at least one of a current flowing through the pre-charging resistor, a voltage applied to the battery, a number of switch-on operations per unit time, a duration of a switch-on operation, and an ambient temperature.
3. The method as claimed in claim 1 , the estimating the temperature of the pre-charging resistor further comprising:
estimating the temperature of the pre-charging resistor based on a temperature model that predicts an inherent heating of the pre-charging resistor as a function of the recorded operating data.
4. A device for limiting a switch-on current of a circuit configured to receive current from a battery, the device comprising:
a connecting unit configured to connect an electrical load to the battery during a switch-on operation;
a pre-charging unit configured to pre-charge the electrical load via a pre-charging resistor during the switch-on operation;
a monitoring unit configured to regularly record operating data including at least one variable that influences a temperature of the pre-charging resistor;
an estimating unit configured estimate the temperature of the pre-charging resistor based on the recorded operating data; and
a protection unit configured to (i) generate a warning signal in response to the estimated temperature of the pre-charging resistor exceeding a first temperature threshold value and (ii) prevent pre-charging of the electrical load via the pre-charging resistor in response to the estimated temperature of the pre-charging resistor exceeding a second temperature threshold value that is greater than the first temperature threshold value.
5. The device as claimed in claim 4 , further comprising:
a control device,
wherein the control device includes the monitoring unit.
6. The device as claimed in claim 5 , wherein the control device and the battery are connected to a CAN field bus.
7. The device as claimed in claim 4 , wherein a first relay is connected in series with the pre-charging resistor and a second relay is connected in parallel to the first relay with the pre-charging resistor.
8. A battery comprising:
a pre-charging resistor configured to pre-charge an electrical load; and
a monitoring unit configured to:
regularly record operating data including at least one variable that influences a temperature of the pre-charging resistor;
estimate the temperature of the pre-charging resistor based on the recorded operating data; and
generate a warning signal in response to the estimated temperature of the pre-charging resistor exceeding a first temperature threshold value; and
prevent pre-charging of the electrical load via the pre-charging resistor in response to the estimated temperature of the pre-charging resistor exceeding a second temperature threshold value that is greater than the first temperature threshold value.
9. The battery as claimed in claim 8 , wherein the battery is configured (i) to connect an electrical load to the electrical network during a switch-on operation, and (ii) to pre-charge the electrical load via the pre-charging resistor during the switch-on operation.