The accurate magnetic model is mandatory for high-performance control of high anisotropy synchronous machines. This paper presents a time-efficient and accurate magnetic model identification based on triangle current injection while the machine under the test is driven at a constant speed by a prime mover. The current injection pattern allows scanning the whole range of current, reducing the identification time compared to the standard constant-speed method (CSM) with the same level of accuracy. The ohmic voltage drop and inverter nonlinearities are compensated by using the average voltage of motor and generator modes. The synchronous reluctance machine is used as a case study for validation through the comparison between the experimental results obtained by the proposed method and the CSM against finite element simulation. Moreover, the temperature variation of the machine winding is measured showing no considerable changes during the identification test.
The high-frequency injection (HFI) method is commonly used for sensorless control of synchronous reluctance motors (SynRMs) at low speeds. Injecting a high-frequency (HF) signal in a predefined direction, referred to as the d-axis, and further demodulating the excited signal in the q-axis are a popular sequence for SynRM position tracking. Injection in the q-axis is not usually considered due to its potential to increase torque ripple. This article proposes a generalized HF pulsating voltage injection approach for sensorless control of SynRM. This approach allows for the arbitrary selection of injection strategy and covers the injection and demodulation procedures in d-and q-axes in detail. Special attention is given to determining the amplitude of the injection voltage, which can extend the usage range of HFI and support sensorless control at high speeds. The effectiveness of the proposed structures is experimentally verified using 15 kW SynRM. During system validation, extra care is taken to investigate the overall system efficiency and vibration levels, including torque ripple issues. This solution contributes to the advancement of sensorless control for SynRM drives.INDEX TERMS High-frequency injection (HFI), motor efficiency, sensorless control, synchronous reluctance motor (SynRM), torque control, variable frequency drives.
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