Dual-Inverter-Controlled Brushless Operation of Wound Rotor Synchronous Machines Based on an Open-Winding Pattern

Abstract

In an open-winding machine, three-phase stator currents can be controlled such that the input armature currents may contain the third-harmonic current component in addition to the fundamental. Considering this attribute of open-winding patterns, a harmonic current field excitation technique for a wound rotor synchronous machine (WRSM) is proposed in this paper based on the control of time-harmonic magneto-motive force. Two inverters connected to both terminals of the stator winding are controlled so that the input armature current generates an additional third-harmonic current component. This third-harmonic component generates a vibrating magnetic field that induces a current in the specially designed rotor harmonic winding. The current is supplied as DC current to the rotor excitation winding to generate a rotor field by using a full-bridge diode rectifier in order to achieve brushless operation. The proposed dual-inverter-controlled brushless operation for a WRSM is executed in ANSYS Maxwell using 2-D finite element analysis to validate its operation and electromagnetic performance.

Brushless field‐excitation method for wound‐rotor synchronous machines

“…The same composite output current shape for armature winding that was previously achieved by a parallel‐inverter‐controlled brushless scheme was later realized by employing an open‐winding pattern‐based WRSM topology in Reference 22. This brushless technique is shown in Figure 1B.…”

“…Hence, it does not require any advanced and complex control design to control the stator currents. Furthermore, the proposed brushless scheme involves a single‐phase inverter and does not require thyristor switches that reduce its size, weight, and cost as compared to the brushless techniques proposed in 12,22 . The three‐phase fundamental current generates the main stator field, whereas the single‐phase third‐harmonic current induces electromotive force (EMF) in the harmonic winding that is rectified to provide direct excitation current to the rotor field winding to achieve brushless operation of the WRSMs.…”

Simplified Brushless Wound Field Synchronous Machine Topology Based on a Three-Phase Rectifier

“…1(b), this topology requires a modification in the machine structure and additional devices such as transformers and single-phase double-conversion converters, which may not be a preferable option for brushless operations in industrial applications. In [10]- [12], the authors proposed brushless topologies based on dual-inverter-based configurations. In [10]- [11], open-winding-pattern-based dual-inverter-fed brushless topologies were proposed to generate an armature current comprising fundamental and third-harmonic current components.…”

High-Efficient Brushless Wound Rotor Synchronous Machine Topology Based on Sub-Harmonic Field-Excitation Technique

“…Besides the high cost, the extraction of rare-earth metals to attain continuous supply for the industries manufacturing PM electrical machines has also raised environmental concerns. This has motivated researchers to explore other options in the field of electrical machines which either require less magnets, as in the case of PM-assisted synchronous reluctance machines, or that require no magnet, such as WRSMs [8][9][10].…”