Silent low speed self-sensing strategy for permanent magnet synchronous machines based on subtractive filtering

The inherent advantages of sensorless control related to reliability, efficiency and costs turn it to be a very interesting technology for automotive applications. Nevertheless, the generation of acoustic noises and current bandwidth limitations due to the injection of HF voltages near zero speed limits its applicability for such high-performance applications. In this work, a newly silent self-sensing strategy, which is achieved through the reduction of the injection frequency, is presented. A novel filtering strategy, based on signal reconstruction, is introduced in order to overcome the bandwidth limitation of the current controller. Moreover, the estimation disturbances in transients are minimized due to the use of a hybrid observer. Experimental results show the effectiveness of the proposed approach.