Electrical driven winch control for on board deck machinery

Abstract

Winches are widely used on board ship’s deck machinery for anchor handling and mooring. The marine winch market was dominated by hydraulic systems and there is a trend to be replaced by more efficient electrical drive system. For both anchoring and mooring control, full load torque is required through the entire speed range including zero speed operation. This poses a challenge for the inverter driven motor control, especially when there is no speed or position sensor. This thesis aims to develop advanced control algorithms of permanent magnet (PM) machine including direct torque control (DTC) and sensorless control for marine winch application. In this thesis, direct torque control, as a new type of high-performance ac driving system after vector control technique, is mainly concerned. Furthermore, since the traditional switch-table based DTC ac motor drive is usually affected by the torque ripple problem and steady-state error problem in torque, this thesis introduced a modified 12-sector DTC control method. The subsystems of traditional DTC system and modified DTC system for permanent magnet synchronous machine (PMSM) are modeled and designed in PSIM software. Then the simulation models of the above two control strategies are also established. Simulation research is conducted and the results are corresponding with theory analysis: the improved system has good dynamic and static performance; less flux and torque ripple especially in the low speed range. The second part of this thesis is to realize sensorless control of DTC control system. Considered the actual situation on board, different methods for high-speed range and low-speed range are discussed. The rotating high frequency (hf) voltage signal injection as low-speed sensorless control method is good for its simplicity and better tracking accuracy, while the back-EMF integral as high-speed method is suitable for its mature industrial applications. And the hf injection method used in this thesis is designed to compatible with the DTC method applied in this thesis, which successfully extended the speed range without sacrificing the simplicity of DTC method.