Thomas Lipo

An induction machine with localized voltage unbalance compensation is disclosed. The use of an induction machine with a voltage unbalance correction compensator (VUC) may be used to maintain proper working conditions of the machine during intervals of voltage unbalance.

With optimized design and modern brushless operation, wound rotor synchronous machines are resurrecting as a strong contender in many applications presently dominated by permanent magnet machines. Considering the notion, this paper introduces a novel brushless synchronous machine topology that utilizes sub-harmonic magnetomotive force (MMF) of its stator winding for desirable brushless operation. It is significant to state that the sub-harmonic MMF component that is used in this novel topology is one-fourth of the fundamental MMF component, whereas, in previous practices, it was half. Moreover, the stator of the machine uses a new winding arrangement of two sets of balanced three-phase windings wound in two layers to produce the fundamental and the sub-harmonic MMF. To achieve the brushless excitation, the rotor utilizes an additional winding that is used to induce the electromotive force (EMF …

The Vernier machine can utilize magnetic-gear effect, which conspicuously improves the torque production over other type of synchronous machines. However, a dual-rotor/dual-stator structure enabled high torque density Vernier design is often unfavorable for industrial applications, due to manufacturing complexity and thermal management challenges. This article successfully addresses this problem, by building magnetic-gear effect into a consequent pole enabled alternating flux barrier structure with single-rotor single-stator (SRSS). In this way, the proposed machine can achieve a superior torque density as a Vernier machine does, while maintaining an equivalent manufacturing complexity as a conventional SRSS synchronous machine. This article begins with elaborating generic analytical equations, which can transform into a Vernier machine or an SRSS synchronous machine. More specifically, the …

This paper proposes a novel brushless synchronous machine topology that utilizes stator sub-harmonic magnetomotive force (MMF) for desirable brushless operation. The sub-harmonic MMF component that is used in this novel topology is one fourth of the fundamental MMF component, whereas, in previous practices, it was half. To achieve the brushless operation, the novel machine uses a unique stator winding configuration of two sets of balanced 3-phase winding wound in 3 layers. For the rotor, additional winding is placed to induce the sub-harmonic component to achieve the brushless excitation. Unlike its predecessors, it utilizes maximum allowable space in the stator to house conductors in all of its slots. To implement the topology, 8-pole, 48-slot sub-harmonic brushless synchronous machine model has been designed. A 2-D finite element analysis (FEA) is used to simulate and validate the performance of the novel machine as a motor. The proposed topology shows better average torque than the existing sub-harmonic wound rotor brushless synchronous machine topologies.

A harmonic excitation brushless synchronous machine has higher power density compared with the traditional aerial three-stage generator due to removing the axial exciter and is suitable for use as an integrated starting-generator (ISG). However, the field current cannot always be generated in the field windings at different rotor positions in the starting mode. A new excitation scheme employing double three-phase phase orthogonal zero-sequence armature currents is proposed in this article. Harmonic electromotive forces and field current can be produced by the zero-sequence rotating excitation magnetic field and almost has no relationship with the rotor positions. In addition, in order to obtain a constant field current during the starting process, a control method of the generated field current is also presented. The rotating speed and field intensity of the zero-sequence excitation magnetomotive forces are both …

This paper presents a new method of automatically formulating path of d-axis current command of surface-mounted permanent-magnet synchronous motor to realize deep flux-weakening operation. The theoretical deduction for flux-weakening regime has been reviewed, and a three segment d-axis current command control strategy with decoupling current control is proposed, which includes maximum torque per ampere, basic flux-weakening and simplified deep flux-weakening mode. The adopted path of utilizing d-axis current command is described in detail. One of its remarkable advantages is that the corresponding converting points between the basic flux-weakening and simplified deep flux-weakening mode can be generated by the given speeds, resulting in the fact that the values of the current floating conversion point and the path connected by the point are far less than the current maximum so as to save …

An electric machine includes a rotor, permanent magnets, a stator, and a stator winding wound about a plurality of teeth to form a number of stator magnetic poles. The rotor includes a rotor core and a plurality of walls that form openings in the rotor core. A permanent magnet is mounted in each of the openings formed in the rotor core. The plurality of permanent magnets are arranged to form a plurality of groups of permanent magnets that are equally circumferentially distributed around the rotor core with an interior polarity on a side of each permanent magnet facing other permanent magnets of the group of permanent magnets to which the permanent magnet is associated that is the same for all of the permanent magnets. Each permanent magnet is arranged to form a rotor pole, wherein a number of rotor poles is greater than the number of stator magnetic poles.

The rotor includes ribs and permanent magnets mounted as spokes in pole pairs. A second wall of each rotor air gap of a plurality of rotor air gaps is parallel to an edge of a permanent magnet of the permanent magnets. A length of the second wall is less than 80% of a length of the edge. A fifth wall of each rotor air gap of the rotor air gaps is formed by a first side of a rib. Each pair of permanent magnets has an associated pair of rotor air gaps of the rotor air gaps. A first rotor air gap of each pair of rotor air gaps of the rotor air gaps is a mirror image of a second rotor air gap of each pair of rotor air gaps. Each pair of rotor air gaps is separated by an associated rib of the plurality of ribs.