Sliding Mode Observer with Exponential Reaching Law for Speed Estimation of a Six-Phase Induction Machine

Area of Science:

• Electrical Engineering
• Control Systems
• Power Electronics

Background:

• Sensorless operation in multiphase electric drives demands precise speed estimation.
• Conventional methods often face challenges with dynamic response, oscillations, and complexity.
• Asymmetrical six-phase induction machines require specialized estimation techniques.

Purpose of the Study:

• To propose a novel sliding-mode observer (SMO) for rotor speed estimation in asymmetrical six-phase induction machines.
• To enhance sensorless operation by improving dynamic response and reducing implementation complexity.
• To eliminate the need for auxiliary low-pass filtering (LPF) stages.

Main Methods:

• Implementation of a sliding-mode observer (SMO) with an exponential reaching law (ERL).
• Utilizing an ERL-based adaptive gain mechanism to avoid LPF.
• Employing Lyapunov-based stability analysis to prove observer convergence.
• Validation through simulations and experimental results on a real-time test bench.

Main Results:

• The proposed SMO + ERL observer achieves fast transient dynamics and reduces chattering.
• Elimination of LPF prevents phase delay and bandwidth reduction, improving signal smoothness.
• Demonstrated stable low-speed operation, effective speed reversal, and reliable performance under load.
• Validated digital implementation for practical multiphase drive applications.

Conclusions:

• The proposed SMO + ERL is a highly effective technique for sensorless speed estimation in multiphase drives.
• It offers improved performance and reduced hardware complexity compared to conventional methods.
• This approach enhances the reliability and efficiency of sensorless multiphase electric drives.