Sensorless control of synchronous reluctance motors based on extended electromotive force model and inductance measurement

Abstract

SUMMARYIn this paper, sensorless control for synchronous reluctance motors (SynRMs) without signal injection and an inductance measurement for position estimation are proposed. In the case of SynRMs, accuracy of inductances is the most important factor in realizing precise position estimation because inductances are largely varied by a magnetic saturation phenomenon. Therefore, the inductance measurement method, which can measure appropriate inductances for position estimation, is important as well as a sensorless control method. The inductance measurement based on the observer is discussed, and the measurement method and the parameter adjustment method for improved stability of the closed loop are proposed. The proposed method can measure inductances easily and be applied for permanent magnet synchronous motors, too. Finally, the proposed sensorless control method is verified experimentally.

An Online Position Error Correction Method for Sensorless Control of Permanent Magnet Synchronous Machine With Parameter Mismatch

“…When there is a phase resistance mismatch as (9), the difference between the estimated and actual derivative current state variables can be derived from (5) as: (12) If the feedback gain of the observer is well designed, then the estimation error of •…”

“…If the nominal parameters used in these methods are different from the actual machine parameters (i.e. parameter mismatch), a DC offset error appears in the estimated position [9]- [12], [15]- [20].…”

“…In order to reduce the effects caused by parameter mismatch, many methods have been proposed, and they can be generally classified into two categories: offline approaches [9], [12], [15], [22] and online algorithms [3], [16]- [20]. One typical offline solution is to fit curves or to build lookup tables of the parameters based on finite element analysis (FEA) results [15].…”

“…One typical offline solution is to fit curves or to build lookup tables of the parameters based on finite element analysis (FEA) results [15]. Others, such as in [9], the q-axis inductance is measured with the help of an encoder. In [12], a pre-determined artificial inductance is introduced to reduce the rotor position error.…”

“…From ( 13) and ( 14), it can be observed that the E-EMF observer is less sensitive to the d-axis inductance mismatch. However, the stator resistance and q-axis inductance may cause the estimated error in the estimated E-EMF, and thus affect the position estimation accuracy [9]- [12].…”