Method of estimating initial rotor position for IPMSMs using subdivided voltage vectors based on inductance variation
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ORIGINAL ARTICLE
Method of estimating initial rotor position for IPMSMs using subdivided voltage vectors based on inductance variation Dae‑Hyun Cho1 · Yeongsu Bak1 · Kyo‑Beum Lee1 Received: 10 March 2020 / Revised: 27 May 2020 / Accepted: 31 May 2020 © The Korean Institute of Power Electronics 2020
Abstract This paper proposes a method for estimating the initial rotor position for an interior permanent-magnet synchronous motor (IPMSM) using subdivided voltage vectors based on inductance variation. Since the stator inductance of an IPMSM varies depending on the rotor position, the current that flows through the entire IPMSM drive system can be different depending on the rotor position when a voltage vector is applied to the stator winding of the IPMSM. Therefore, the rotor position can be estimated using the differences in the currents. In the conventional method, which uses six voltage vectors to estimate the initial rotor position, the estimated position error is increased in specific regions where the phase angle of the applied voltage vector is remarkably different from that of the N pole of the rotor. This paper presents an advanced method using subdivided voltage vectors to estimate the initial rotor position more precisely in a specific region. The effectiveness of the advanced estimation method is verified by simulation and experimental results. Keywords Interior permanent-magnet synchronous motor · Initial rotor position · Inductance variation · Subdivided voltage vectors
1 Introduction Currently, interior permanent-magnet synchronous motors (IPMSMs) are widely used in various industrial fields due to their high power density, high torque density, and high efficiency [1–6]. Since the rotor position of an IPMSM is needed to implement the initial drive and precise vector control of the IPMSM, a position sensor such as a resolver or an absolute encoder is attached to the shaft of the rotor. If the precise rotor position is not obtained, it can result in a failure of the initial drive or a deterioration of the torque control response of the IPMSM. However, a position sensor increases the system cost and volume, while decreasing reliability due to its noise [7, 8]. Therefore, research has been conducted to estimate the initial rotor position without sensors. Two representative methods are used to estimate the initial rotor position: high-frequency injection and voltage pulse methods.
* Kyo‑Beum Lee [email protected] 1
Department of Electrical and Computer Engineering, Ajou University, Suwon, South Korea
A high-frequency injection method is implemented by applying a high-frequency voltage or current to a stationary or rotating reference frame [9–12]. It requires complex signal processing including digital filters to estimate the initial rotor position. In addition, it induces audible noise. The voltage pulse method uses inductance variation as a function of the rotor position. In this method, the initial rotor position can be estimated by the difference in the currents generated by applying voltage pulses
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