Position Sensor-less and Adaptive Speed Design for Controlling Brush-less DC Motor Drives

TL;DR

This paper introduces a sensor-less, adaptive control method for BLDC motors using a sliding mode observer, RLS estimation, and MMRAS to improve robustness, reduce noise, and eliminate the need for filters.

Contribution

It presents a novel integrated approach combining sliding mode observer, RLS, and MMRAS for sensor-less and adaptive speed control of BLDC motors.

Findings

Effective back-EMF estimation with reduced noise.

Successful real-time load torque and inertia estimation.

Improved speed control robustness and response.

Abstract

This paper proposes a method for direct torque control of Brushless DC (BLDC) motors. Evaluating the trapezium of back-EMF is needed, and is done via a sliding mode observer employing just one measurement of stator current. The effect of the proposed estimation algorithm is reducing the impact of switching noise and consequently eliminating the required filter. Furthermore, to overcome the uncertainties related to BLDC motors, Recursive Least Square (RLS) is regarded as a real-time estimator of inertia and viscous damping coefficients of the BLDC motor. By substituting the estimated load torque in mechanical dynamic equations, the rotor speed can be calculated. Also, to increase the robustness and decrease the rise time of the system, Modified Model Reference Adaptive System (MMRAS) is applied in order to design a new speed controller. Simulation results confirm the validity of this recommended method.