The VFD control system is able to rectify the constant voltage, constant frequency AC power into DC, then change into AC power with variable frequency and voltage via inverter to supply power for AC motors. By this process, the VFD control system performs the control of speed and torque for tig winch, rotary table, mud pump or bit-feed motor, and to perform stepless adjustment, satisfying driving requirement.

The system adopts the "zero speed and large torque frequency conversion control technology" independently developed by Hande, and the controller is equipped with "speed adaptive full-order observer control algorithm". Use "one-to-one" control scheme (ZJ70DB) or turntable winch switching scheme (ZJ40DB).

The PLC system uses PROFIBUS fieldbus communication to realize the control, monitoring and fault judgment of the system. The relay can also be used for emergency operation, and the control signal can be transmitted through the multi-core cable.