An Electrical Machine with Integrated Drive LCL Filter Components

Abstract

In recent years, integrated passive components technology has gained significant popularity in integrated drives research. An integrated drive may be considered to be a full mechanical integration of the machine, power electronic converter and passive components into a single package. This approach is important for applications such as traction motors, aerospace, electric vehicles and cars where space, mass or volume constraints are high. Incorporation of electromagnetic components, such as line filters, into electric machines can be achieved by sharing the existing machine's magnetic circuit with the filter component. In this paper part of an LCL line filter has been chosen to be integrated with a permanent magnet synchronous machine. An LCL filter has been selected as it has lower inductance compared to other input filter types such as LC and L filters. This paper also presents a several novel techniques for integrating the largest portion of LCL input power filter which is the 3-phase ac inductors located in the drive side producing a single mechanically packaged unit without significant increase in size and loss which in turn achieves high power density. Different integrated 3-phase input inductors designs have been simulated with finite element analysis to prove the effectiveness of integration of passives within the machine structure. In each case the design has been iteratively optimised to determine the optimal mass of copper and core for the integrated filter inductors targeting parity in power density when compared to a traditionally separated package. The paper demonstrates that an approach utilising a double slot machine with input filters wound into the outermost slots was the most appropriate choice in terms of power density compared to other proposed methods.

Integrating the magnetics of an LCL filter into a high speed machine with pre-compressed coils

“…The integration of solely drive side inductors (L2) achieves lower volume and losses compared to a traditional discrete 3-phase drive side inductors by 86% and 22% respectively. For the selective method, the stator lamination of the original PM machine was modified to double as 3-phase LCL filter inductors integrated into the machine structure [13]. The advantage of proposed stator geometry with integrated inductors is to limit the interaction between the magnetic fields of filter inductors and that in the core back due to the PM machine.…”

“…The envelope of the filter components are rarely congruent with that of the machine leading a poor utilization of the available volume in which to install the drive, thus it becomes desirable to more effectively integrate the various components of the drive in a more compact manner. Integrated motor drives offer potential benefits such as direct replacement of inefficient direct on line motors, higher power density and lower time and cost of installation compared to separate drive and motor systems [12] and [13].…”

Novel Permanent Magnet Synchronous Motor With Integrated Filter Inductor, Using Motor's Inherent Magnetics

“…If the stator back iron of the machine is operating linearly then the presence of ring flux due to toroidal winding will not affect the main flux. Authors of [16,17] presented a structural integration of grid side passive LCL filter into the high-speed PMSM which achieves high power density. Both inductors are wound into the outermost slots of the double slot machine.…”

Design Consideration of a High-Speed Integrated Permanent Magnet Machine and its Drive System

“…The integration of solely drive side inductors (L2) achieves lower volume and losses compared to a traditional discrete 3-phase drive side inductors by 86% and 22% respectively. For the selective method, the stator lamination of the original PM machine was modified to double as 3-phase LCL filter inductors integrated into the machine structure [16]. Fig.…”

“…The advantage of the proposed IDSM stator geometry is to limit the interaction between the magnetic fields induced by filter inductors and the magnetic fields in the core back induced by the permanent magnets. Since the integration of three-phase drive side inductors (L2) was achieved as presented in [16], further work has been carried out to integrate the grid side inductors (L1) of input LCL filter. The specifications of the drive and LCL filter are given in Table I.…”