The system (20, 30) for controlling the opening and/or closing of a normally-closed machinery brake (1) opening by means of at least one magnetizing coil (9) and closing by means of at least one closing spring (3) comprises: at least one estimation and control loop (20) according to the invention and at least one measuring and control circuit (30) according to the invention, which are connected or can be connected to each other, and of which a) the estimation and control loop (20) is configured to use an input (I (t) ) produced by the measuring and control circuit (30), and b) the measuring and control circuit (30) is configured to use the modulation reference (U3B) produced by the estimation and control loop (20) for connecting the voltage (U9) to be connected over the magnetizing coil (9).