Publication Detail


Arijit Banerjee, Michael S Tomovich, Steve Leeb, James Kirtley, Abdelhamid Ouroua

If a doubly fed machine is used as the prime mover in a hybrid DC/AC shipboard electrical system, both the AC and DC elements of the power system can be utilized in order to improve efficiency, weight, volume, and sizing of the rotor power electronics. The purpose of this report is to develop models of this doubly-fed machine (DFM) for enabling the evaluation of propulsion performance under sea-state conditions. A second purpose of this work is to provide models that can be used to develop active control for the DFM.

The DFM has two modes of operation. In the first mode of operation, the DC source is used onthe DFM stator, and the rotor is driven with a power electronics drive. The DC on the stator makes the machine behave like a permanent magnet machine (or a synchronous motor). The DFM is operated in this mode until the shaft speed reaches the synchronous speed, as determined by the AC source frequency; at this point the stator supply is switched from DC to AC. The AC on the stator enables the power electronics drive on the rotor to accelerate the shaft past synchronous speed. In this mode, the machine behaves like a doubly fed induction machine. Additionally, reactive power can be controlled in AC mode, which gives added flexibility in system design.

In order to successfully implement such a scheme, some interesting things must be done from a controls perspective in order to minimize transient effects on the system.Namely, a synchronizer is essential to determine the correct instant ofswitching in order to minimize the transients on torque and speed. A complete control scheme is devised that uses the stator flux reference frame. A novel hybrid flux estimator was implemented in order to overcome these offsets. This control scheme was then verified using MATLAB SIMULINK simulations and the controller was tuned to enable bumpless control of the DFM.

type: Technical reports

Parent Project

Project No.: 2014-ESRDC-04-LEV
Title: ESRDC - Designing and Powering the Future Fleet Additional Task 1.4.3 Concept Refinement