Method for controlling a brake system of a motor vehicle

A method for controlling a brake system of a motor vehicle, which includes an electronic control unit, an electric generator and a number of friction brakes being associated with axles of the motor vehicle, and the total deceleration of which is composed of a first deceleration component provided by the electric generator and a second deceleration component provided by the friction brakes, the method changing the ratio of nominal values of the deceleration components relative to each other comprising the steps of:

• measuring an actual deceleration;
• determining a first nominal deceleration for a first subset of the number of friction brakes, the first subset being associated with one common first axle, a second nominal deceleration for a second subset of the number of friction brakes, the second subset being associated with one common second axle, and a third nominal deceleration for the electric generator, during each of a plurality of measurement phases during one brake application, each measurement phase having a respective predetermined minimum of at least one of the first and second deceleration components and the first deceleration component contributing more than half of the total vehicle deceleration in at least one of the measurement phases,
• determining a first efficiency ratio for the first subset of the number of friction brakes, the first efficiency ratio representing a ratio between the actual deceleration and the first nominal deceleration;
• determining a second efficiency ratio for the second subset of the number of friction brakes, the second efficiency ratio representing a ratio between the actual deceleration and the second nominal deceleration;
• determining a third efficiency ratio for the electric generator, the third efficiency ratio representing a ratio between the actual deceleration and the third nominal deceleration;
• determining a first correction value from the first efficiency ratio and the third efficiency ratio;
• determining a second correction value from the second efficiency ratio and the third efficiency ratio;
• applying the first correction value to the first nominal deceleration;
• and
• applying the second correction value to the second nominal deceleration;
• wherein the minimum deceleration component of the electric generator amounts to roughly 0.95 of the vehicle deceleration in a first phase of measurement, and in a second phase of measurement the minimum deceleration component of the friction brakes of the second axle amounts to 0.15 of the total deceleration of the motor vehicle and the deceleration component of the friction brakes of the first axle amounts to at most roughly 0.05 of the total deceleration of the motor vehicle, while the minimum deceleration component of the friction brakes of the first axle amounts to roughly 0.5 of the total deceleration of the motor vehicle in a third phase of measurement, with the electric generator being connected to the first axle.