Brake device for a vehicle and method for operating a brake device for a vehicle

A method for operating a brake device for a vehicle to control a braking action of the vehicle, the method comprising the following steps:

• detecting a need to carry out a braking action with a brake device, the brake device including:
• a brake actuator device, and
• a controller which is connected to and/or included in the brake actuator device, the controller further being connectable to an electric machine of the vehicle;
• ascertaining an operating state on the electric machine and, from the operating state, ascertaining a generatable second brake torque of the electric machine in generator mode, and comparing the generatable second brake torque to a specified total brake torque on a vehicle;
• and
• generating a first brake torque using the brake actuator device and generating the second brake torque using the electric machine, the first brake torque and the second brake torque being generated together as a total brake torque on the vehicle, wherein an operating parameter for an operation of the brake actuator device is adjusted, thereby reducing or increasing the first brake torque of the brake actuator device to provide, together with the second brake torque, at least the specified total brake torque to the vehicle, wherein the controller is connected to an on-board power supply of the vehicle, wherein a voltage at the on-board power supply is ascertained and, when the voltage at the on-board power supply drops below a first threshold value, an actuation voltage and/or an actuation current of the brake actuator device is limited and, when the voltage at the on-board power supply drops below a second threshold value that is lower than the first threshold, the brake actuator device is switched off when the second brake torque by itself reaches the specified total brake torque on the vehicle.