Workshop on SRM drives an alternative for E-traction SRM drives an alternative for E-traction Pere Andrada GAECE, DEE EPSEVG. UPC-BARCELONATECH, Vilanova i la Geltrú, Spain pere.andrada@upc. I. INTRODUCTION Electrification of road vehicles is one of the most consistent initiatives to achieve a clean, environmentally friendly and efficient transport system. The choice of the electric machine for the powertrain is an important consideration, nowadays tilted towards permanent magnet synchronous machines. However, rare earth permanent magnet supply drawbacks open up new prospects for other types of machines, such as switched reluctance machines (SRM). This Workshop, Switched reluctance motor drives an alternative for E-traction, aims to deepen into the potential of SRM for electric traction, to be a meeting point for groups that are currently working on the development of SRM drives and an opportunity to establish future collaborations. The Workshop consists of two parts. In the first part, participants will present papers about issues related with switched reluctance machines for electric traction applications. In the second part, they will discuss what aspects slow down the application of SRM drives for electric traction and their possible solutions. The sales of hybrid electric vehicles (HEVs) and battery electric vehicles (BEVs) have reached significant levels worldwide and are expected to grow even more in the coming years [1]. In order to further boost this growth, technological improvements and cost reductions have to be done not only in the electric storage system, mainly batteries, but also in the electric propulsion system, traction drives. Right now most of the traction drives for HEVs and BEVs are permanent magnet synchronous motor (PMSM) drives due to their high power and torque density, wide speed range and high efficiency. The main drawback of the PMSM drives is the use of rare earth permanent magnets. Although rare earth elements are not very scarce, some circumstances as:  The 50% of reserves are located in China.  China, in addition, controls most of the world production of rare earth permanent magnets.  The growing demand of permanent magnet for the green industries (wind generation, electric vehicles,...).  The experience of past turbulences (2011) in the price of the permanent magnets. These reasons advise to reduce the weight of permanent magnet into the electric machines or even to dispense of it. Thus, nowadays, there is a great interest in the development of magnet-less electric drives; the most relevant drives in this category are: induction motor (IM) drives, synchronous reluctance motor (SyncRM) drives and SRM drives [3-6]. II. SRM DRIVES This Workshop is devoted, exclusively, to one of these candidates of magnet-less drives the SRM drives. From the point of view of electromechanical conversion, SRM is a doubly salient pole device with single excitation that usually works strongly saturated [7]. The rotary SRM can be classified according their airgap flux direction as radial, axial and transverse flux machine. In radial flux SRM the air gap flux is mainly in the radial direction relative to the axis of rotation. This type of SRM, usually have a cylindrical shape with a stator and a rotor that can be internal, the most common disposition, or outer. In axial flux SRM the air gap flux is mostly parallel to the axis of rotation. The stator and rotor are parallel plates arranged perpendicular to the axis of rotation. In transverse flux SRM the air gap flux is tangentially, transverse, to the axis of rotation [8]. In all cases, torque is produced by the tendency of its rotor to move to a position where the inductance of the excited phase winding is maximized, i.e. to reach the alignment of stator and rotor poles. Therefore, a power converter with solid-state switches is needed to generate the right sequence of phase commutations for which it is required to known the position of the rotor. In variable speed applications, the SRM operates in one of the following three control modes: current mode, voltage mode and single pulse mode. Generally the SRM is controlled in the low speed range by current control maintaining current within a given hysteresis band or by voltage control using PWM. At high speeds single pulse control is used adapting the conduction period and the current waveform to the speed and torque requirements. Vilanova i la Geltrú, Spain. February 2, 2018 7