Mechanical Torque Ripple From a Passive Diode Rectifier in a 12 kW Vertical Axis Wind Turbine

Abstract

PostprintThis is the accepted version of a paper published in IEEE transactions on energy conversion. This paper has been peer-reviewed but does not include the final publisher proof-corrections or journal pagination.Citation for the original published paper (version of record):Rossander, M., Goude, A., Eriksson, S. (2017) Mechanical torque ripple from a passive diode rectifier in a 12 kW vertical axis wind turbine. Abstract-The influence of passive rectification on the mechanical torque of a permanent magnet generator for a directly driven vertical axis wind turbine has been studied. Passive diode rectification introduce electromagnetic torque ripple from the generator. The conversion of electromagnetic torque ripple into mechanical torque ripple and rotational speed ripple has been modelled, analytically evaluated and simulated. The simulations have been compared to measurements on an open site 12 kW prototype. A parameter study with the model illustrates the impact of shaft torsional spring constant, generator rotor inertia, generator inductance and dc-link capacitance. The results show that the shaft and generator rotor can be an effective filter of electromagnetic torque ripple from diode rectification. The measured mechanical torque ripple amplitude on the prototype is less than ±0.9% of nominal turbine torque. The measurements compare well with the simulations.

Impact of Single and Combined Faults Composed of Rotor Eccentricity and Stator Interturn Short Circuit on Electromagnetic Torque Ripples in Synchronous Generator

“…e novelty of this paper primarily lies in the following three issues. (1) We investigate the EMT ripple properties not only under the single SAGE fault and the single SISC fault but also in the combined fault cases which are rarely taken into account by other studies. (2) We specifically design and manufacture a novel fault simulating generator which has been rarely reported and is able to simulate both the single and the combined faults composed of SAGE and SISC at the same time.…”

“…Since EMT is the resisting moment, its ripple properties are closely related to the output stability of the generator. On the one hand, large EMT ripples will lead to the overfrequent adjustment of the automatic control system to modify the input mechanical moment, and obviously this is harmful for the generator set [1]. On the other hand, intensive EMT ripples will cause the torsional vibration of the shaft and may lead to the fatigue of the shaft material after a long-term performance [2].…”

Investigation of Permanent Magnet Demagnetization in Synchronous Machines during Multiple Short-Circuit Fault Conditions

“…An increase in torque could give problems with increased vibrations, especially at lower frequencies when the damping from the generator and shaft dynamics is lower. Therefore, low vibrational frequencies are more easily transferred through the generator and shaft to the turbine [30].…”

Deployment of onshore wind turbine generator topologies: Opportunities and challenges

“…To improve the cost of energy competitiveness of the FPC over the PC, diode-rectification, which is cheaper than controlled-rectification, is applied in the machine-side converter. 47 This improves the overall efficiency and AEP but is possible only in combination with the EESG and PMSG topologies since diode rectification cannot provide back-back capability for magnetization in the SCIG topology. The major downside here is the ensuing high torque pulsation due to the sixth order harmonics from uncontrolled rectification.…”