Method for controlling a torque performance of an electrical pitch motor, an electrical pitch-control system and use thereof

A method for controlling a torque performance of an electrical pitch motor in a system comprising an electrical pitch-control system, said pitch motor controls a turbine blade, said pitch-control system comprises:

• a first unit comparing a received reference pitch-angle Pr with an actual pitch-angle Pa of the turbine blade, said Pa-value is registered by and received from a resolver, and the first unit further regulates the pitch-angle of the turbine blade according to the received pitch-angle values;
• an electrically connected second unit comparing a reference-speed Sr received from the first unit with an actual speed Sa of the rotational speed of the motor, said resolver measures and calculates the actual speed Sa which is sent to the second unit and the second unit regulates the rotational speed of the motor according to the received speed values;
• an electrically connected third unit comparing a reference torque Tr of the motor received from the second unit with the actual torque Ta of the motor, said third unit regulates the torque performance of the motor according to the received reference torque Tr;
• a first overload unit between the third unit and the motor;
• and
• a second overload-unit receives an error-speed-signal Se which is the difference between Sr and Sa registered by the second unit, said second overload unit compares Se with a maximal allowable speed value Smax, and the second overload unit sends a signal to the motor for the regulating of the torque performance of the motor, said signal is a function of the value of Se.