An Improved Super-Twisting High-Order Sliding Mode Observer for Sensorless Control of Permanent Magnet Synchronous Motor

Abstract

This article presents an improved super-twisting high-order sliding mode observer for permanent magnet synchronous motors to achieve high-performance sensorless control. The proposed observer is able to simultaneously estimate rotor position and speed, as well as track parameter disturbances online. Then, according to the back-EMF model, the sensorless observer is further constructed to improve the estimation effect. The estimated rotor position and speed are used to replace the actual values detected by the sensor, and the estimated parameter disturbances are considered as feedback values to compensate the command voltage. In this way, not only is the estimation accuracy improved, but the robustness against uncertainties is also enhanced. Simulation and experimental results show that the proposed observer can effectively track the rotor position and speed and obtain good dynamic and steady-state performance.

Saliency Model Extension for Sensorless Initial Position and Polarity Detection of Permanent Magnet Synchronous Motors

“…Sensorless methods for PMSMs determine the rotor position in terms of electrical angle without a mechanical position sensor usually based on phase current measurements and a suitable machine model. Sensorless control techniques that rely on the fundamental excitation model are capable of providing high-performance control above about 3 % of the nominal speed when the back electromotive force (back-EMF) is sufficiently large [10]- [16].…”

“…The voltage equation of our three-phase star-connected PMSMs at a standstill takes the form of (11) after substituting the quadratic flux-linkage (10) into the voltage equation (2).…”

“…The idealized model predicts the mean values correctly but the data shows third spatial harmonics. We decided not to include these third spatial harmonics in the model to ensure that the description of the quadratic term of the flux model (10) requires only a single new machine parameter, the polaritydependent saliency coefficient Γ 0 .…”

“…We formulated the polarity-dependent quadratic term of the flux-current function in the most general form mathematically possible, therefore, the proposed flux-linkage (10) and voltage equations (11) are applicable to any three-phase star-connected PMSM. The parameter identification method presented in Section IV is also applicable to any three-phase star-connected PMSM, however, it requires access to the star point of the motor and has additional hardware requirements depending on the desired accuracy.…”

“…Conventional PMSM drives utilize a shaft-mounted optical encoder or a resolver to determine the rotor position. In many industrial installations, the presence of the shaft sensor may substantially reduce the overall ruggedness of the drive; in others, it may add significantly to the cost and size of the drive [8]- [10]. To design a more robust, cost-effective and, therefore, more competitive PMSM drive system, it is key to eliminate shaft-mounted sensors as well as related electronics and wiring by introducing position-sensorless control schemes.…”