Method For Determining A Surface Regeneration Parameter Of A Contact Surface Of A Contactor, Method For Determining An Ageing Factor Of A Contact Surface Of A Contactor Taking Into Account A Surface Regeneration Parameter, And Method For Regenerating A Contact Surface Of A Contactor

A method for determining an ageing factor of a contact surface of an electrical contactor in a vehicle, wherein the ageing factor is representative of an ageing state of the contact surface of the contactor, wherein the ageing factor is a progressive counter, the value of which is changed in dependence on opening and closing of the contactor, the method comprising:

• determining a differential voltage across the open contactor;
• determining a first addition element for the ageing factor based on the determined differential voltage;
• closing the contactor if a current ageing factor, which is calculated based on the last known ageing factor before the closing of the contactor and adding of the first addition element, is below a threshold value;
• determining a surface regeneration parameter, which is representative of the regeneration of the contact surface of the contactor while the contactor is closed, wherein the surface regeneration parameter is determined based on a load current flowing through the closed contactor and a duration for which the contactor is closed;
• determining a subtraction element for the ageing factor in dependence on the determined surface regeneration parameter;
• determining the load current on the closed contactor immediately before the opening of the contactor;
• determining a second addition element for the ageing factor based on the load current which was determined immediately before the opening of the contactor,
• opening the contactor;
• and
• determining a current ageing factor of the contactor after the opening of the contactor based on the last known ageing factor before the opening of the contactor and adding of the second addition element and subtracting of the subtraction element.