A Study for Improvement Performance Characteristics of Driving Permanent Magnet Type Synchronous Motor without Position Sensor at Low Speed Range

Abstract

A development of EV in practical use is studied in many industrial field. The driving system of EV requires compact size, high efficiency and low noise generation. Synchronous motor has many advantages against to induction motor at the point of machine size, weight, power factor and efficiency. However, to get high performance we require position sensor when driving synchronous motor. But, it is better that we reduce position sensor in terms of cost and reliability. So, we reported “Position Sensorless Control of DC Blushless Motor using Current-Source PWM Inverter”.
This system has the characteristics of low switching frequency keeping high performance and low noise generation. But this method estimates the rotor position with the induced electromotive force difference from between modeling and detection. Therefore, in a low speed region, it is difficult to detect voltage precisely.
In this paper, we proposed the improvement of performance characteristics at low speed range. In section 2, we explain the outline of driving system and problems. We show the precise position detecting method with flux estimator in section 3. We presented the experimental result of testing system and that this method is in practical use in section 4. From experimental results, we cleared that this method improve the start, stop and low speed driving characteristics without any additional unit to the previous system.