Abstract
Aiming at the position sensorless control system of permanent magnet synchronous motor (PMSM), an improved high-frequency square wave (HFSW) signal injection scheme considering nonlinear inductance variation in d-q axis is proposed and implemented in this paper. Compared with the existing model, the modified scheme can take the dynamic variation of d-q axis inductance under different operation conditions into consideration by offsetting the resulting high-frequency incremental (HFI) current harmonic components, thus effectively suppressing the estimation error of the rotor position. The experimental results verify that the improved scheme proposed in this paper can not only improve the estimation accuracy of rotor position impaired by the non-linear variations of d-q axis inductance but also maintain the good steady-state and dynamic performance of traditional schemes.
Highlights
Permanent magnet synchronous motors (PMSM)1 have been widely used in industrial applications by virtue of their unique advantages, such as high efficiency, high torque, and wide constant power range
As an alternative to mechanical sensors, rotor position sensorless technology is of great significance in practical applications
In view of the above problems, this article analyzes and improves the conventional high frequency square wave (HFSW) injection scheme by offsetting scitation.org/journal/adv the harmonic components in the high-frequency incremental (HFI) current caused by the nonlinear d-q axis inductance variation, and a sensorless PMSM motor prototype was developed and tested to verify the feasibility of the improved HFSW injection scheme
Summary
Permanent magnet synchronous motors (PMSM) have been widely used in industrial applications by virtue of their unique advantages, such as high efficiency, high torque, and wide constant power range. The high frequency square wave (HFSW) injection method is one of sensorless technologies, which demodulates the rotor position information from HF response. Scitation.org/journal/adv the harmonic components in the high-frequency incremental (HFI) current caused by the nonlinear d-q axis inductance variation, and a sensorless PMSM motor prototype was developed and tested to verify the feasibility of the improved HFSW injection scheme. It can be found that the variation range of Ld (peak to average value of d-axis inductance variation) accounts for 17.2% of its average value Such change of Ld will obviously lead to the significant increase of position estimation error. Apparently seen that, as the load current increases, the average value of Ld decreases while the variation range increases correspondingly, which means the dynamic variation of Ld will have an impact on sensorless performance of HFSW especially at large load currents and must be fully considered in the practical control systems
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