Abstract: A method for operating an energy coupling device electrically coupling a high-voltage on-board electrical system designed for d.c. voltage to a low-voltage on-board electrical system designed for d.c. voltage, having a high-voltage energy converter connected to the high-voltage on-board electrical system and a low-voltage energy converter connected to the low-voltage on-board electrical system, which are electrically coupled by means of a d.c. voltage intermediate circuit. The energy converters are controlled by a control unit. The degrees of conversion efficiency of the energy converters are ascertained and an intermediate circuit d.c. voltage of the d.c. voltage intermediate circuit is set as a function of a total degree of efficiency produced by the sum of the degrees of conversion efficiency in order to maximize the total degree of efficiency.

Abstract: An energy supply vehicle for supplying an electrically drivable motor vehicle with an electrical energy. A drive unit for moving the energy supply vehicle, an electrical energy source for supplying electrical energy for the electrically drivable motor vehicle, and an electrical coupling device for electrical coupling the electrical energy source to the electrically drivable motor vehicle in order to transfer the electrical energy from the electrical energy source to the electrically drivable motor vehicle having a control unit including a communication device and is designed to guide the energy supply vehicle as a self-driving and remotely controlled vehicle and to control the electrical coupling device for an automatic electrical coupling of the electrically drivable motor vehicle.

Abstract: A method for operating an energy coupling device electrically coupling a high-voltage on-board electrical system designed for d.c. voltage to a low-voltage on-board electrical system designed for d.c. voltage, having a high-voltage energy converter connected to the high-voltage on-board electrical system and a low-voltage energy converter connected to the low-voltage on-board electrical system, which are electrically coupled by means of a d.c. voltage intermediate circuit. The energy converters are controlled by a control unit. The degrees of conversion efficiency of the energy converters are ascertained and an intermediate circuit d.c. voltage of the d.c. voltage intermediate circuit is set as a function of a total degree of efficiency produced by the sum of the degrees of conversion efficiency in order to maximize the total degree of efficiency.

Abstract: An energy supply vehicle for supplying an electrically drivable motor vehicle with electrical energy. A drive unit for moving the energy supply vehicle, an electrical energy source for supplying electrical energy for the electrically drivable motor vehicle, and an electrical coupling device for the electrical coupling of the electrical energy source to the electrically drivable motor vehicle in order to transfer the electrical energy from the electrical energy source to the electrically drivable motor vehicle having a control unit including a communication device and is designed to guide the energy supply vehicle as a self-driving and remotely controlled vehicle and to control the coupling device for the automatic electrical coupling of the electrically drivable motor vehicle.