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 that the first unit further regulates the pitch-angle of the turbine blade according to the received pitch-angle values,
• after the first unit an electrically connected second unit said second unit compares 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 send to the second unit and that the second unit regulates the rotational speed of the motor according to the received speed values,
• after the second unit an electrically connected third unit comparing a reference torque Tr of the motor,
• said value is received from the second unit, and
• with the actual torque Ta of the motor, said third unit further regulates the torque performance of the motor according to the received torque-references;
• said control system further comprises a first overload unit between the third unit and the motor wherein
• the control system further comprises a second overload-unit said 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 that 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.

An electrical pitch-control system adapted to control a torque performance of an electrical pitch motor said pitch-control system comprises a first unit comprising a first summator adapted to compare a received reference pitch-angle Pr with an actual pitch-angle Pa of a turbine blade, said Pa-value is provided by a resolver, and that the first unit further comprises a first control unit adapted to regulate the pitch-angle of the turbine blade, after the first unit an electrically connected second unit comprising a second summator adapted to compare a reference-speed Sr received from the first unit with an actual speed Sa of the rotational speed of the motor, measured by the resolver, and a second a second control unit adapted to regulate the rotational speed of the motor and after the second unit an electrically connected third unit comprising a third summator adapted to compare the reference torque Tr of the motor, said value is received from the second unit, with the actual torque Ta of the motor and that the third unit further comprises a third control unit adapted to regulate the torque of the motor, said control system further comprises a first overload unit between the third unit and the motor, wherein the control system further comprises a second overload-unit said second overload unit is adapted to receive an error-speed-signal Se which is the difference between Sr and Sa registered by the second unit, said second overload unit is adapted to compare Se with a maximal allowable speed value Smax, and the second overload unit is adapted to send a signal to the motor at which signal the torque performance of the motor is regulated.