Pitch drive system with a switching device controlled back-up power supply and method thereof

摘要

A wind turbine pitch drive system, comprising an electric grid for supplying electrical power, a motor for driving a pitch actuator, an electronic converter for controlling the motor and a back-up energy storage unit for supplying electrical power, wherein the electronic converter comprises a DC-link capacitor bank, and the system furthermore comprises a switching device for selectively connecting the DC-link to the back-up energy storage unit, and a frequency generator for controlling the switching device. A suitable method is also disclosed.