ELECTRICAL AND COMPUTER ENGINEERING SEMINAR SERIES
General Motors Advanced Technical Center
Thursday, April 26, 2018
3:00 p.m. - 4:00 p.m.
“Electric Motor Torque Ripple Mitigation Strategies – Current Regulator Design Studies”
Interior permanent magnet synchronous motor (IPMSM) is widely used for many industrial applications such as electric vehicle(EV) powertrain, compressor and home appliances due to its high-power density and wide speed range. However, IPMSM have relatively high torque ripple compared to surface PMSM. Literature survey shows there are several effective torque ripple mitigation strategies both from machine design and controls perspective. In this presentation, the problem is studied from a controls mitigation perspective with focus on enhancements to industry standard complex PI current regulators. we present two cases studies a) electric transmission oil pump motor b) traction motor, with focus on potential algorithm design enhancements to mitigate torque ripple. With electric transmission oil pump motor application, we present harmonic current regulator that works with fundamental synchronous reference frame regulator and highlight some of the practical challenges with experimental results. In case study with traction motor application we propose a new current controller with modified decoupling and feed forward voltages for a permanent magnet synchronous motor (PMSM) drive. In designing the controller, an improved voltage model, which is different from existing models in that it reflects all the nonlinear characteristics of the motor, is considered. In an actual PMSM, unintentional distortion occurs in inductance and flux due to magnetic saturation and structural asymmetry. The effects of such distortion on voltage ripple are analyzed and the effect of voltage distortion on current control is analyzed. Based on the voltage model, a decoupling controller is developed to effectively separate the d-q current regulators. The controller produces compensation voltages using the current error of the other axis. The proposed current controller aimed at compensating all nonlinearities of PMSM enables high-performance operation of the motor.The feasibility of the proposed current control scheme is verified by experimental results.
Dwarakanath Simili, received his BS in Electrical Engineering from Visvesvaraya Technological University in Bangalore, India, and MS in Mechanical and Aerospace Engineering from Illinois Institute of Technology, Chicago, in 2003 and 2007 respectively.
His work experience includes project assistant at Indian Institute of Science (IISc, Bangalore,’04) in aerospace department, involved in analysis and design of variable structure control for UAVs. After completion of MS he started work at Caterpillar, Peoria, IL as controls engineer in power electronics and controls division involved in products like D7E (track type Dozer) and 797E (mining trucks). He joined General Motors Advanced Technical Center in, Torrance CA in 2010 and has since been involved in development of electric motor control algorithms and calibration on products such as Chevy Spark-EV, Cadillac ELR, Gen2 Chevy Volt and Chevy Bolt. In 2017 he received the Charles”Boss”Kettering award, highest GM recognition for technical innovation for contributions in Design and Control of Chevy Bolt Motor . He holds 4 US patents and is currently Engineering Group Manager for Electric Drive- Controls, Global Propulsion Systems in Pontiac, MI.
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