System and method for improving speed control of a pitch drive system of a wind turbine

A method for improving speed control of a pitch drive system of a wind turbine, the method comprising:

• coupling a battery assembly having, at least, a first battery and a second battery to the pitch drive system, each of the first and second batteries a positive terminal and a second terminal, the pitch drive system having a direct current (DC) motor including an armature and a series-field winding;
• connecting a plurality of diodes between the battery assembly and the series-field winding, the plurality of diodes connected to the battery assembly between the negative terminal of the first battery and the positive terminal of the second battery;
• connecting an additional diode the positive terminal of the first battery of the battery assembly and the DC motor separate from the plurality of diodes connected so as to prevent power regeneration back into the battery assembly;
• and,
• controlling a current to the series-field winding via the plurality of diodes so as to ensure a field flux of the series-field winding does not equal zero, thereby improving speed control of the pitch drive system.