Sensorless Control Techniques for Permanent Magnet Synchronous Motors
Summary
The sensorless control of permanent magnet synchronous motors (PMSMs) is critical for reducing system complexity and improving reliability. By eliminating mechanical position sensors, drive systems achieve lower cost, enhanced robustness and reduced maintenance. Sensorless techniques estimate rotor position and speed from electrical measurements and mathematical models. Principal methods include back EMF observation, where induced voltages reveal rotational dynamics; high-frequency signal injection, which exploits rotor saliency to extract position information; and observer-based strategies such as sliding-mode, extended Kalman and Luenberger observers, which combine state-space models with estimation algorithms. Model reference adaptive systems adjust parameters online to maintain accuracy amid load or temperature variations. Startup at zero or low speed is addressed by current-frequency methods and pulsed injection schemes to provide initial position estimates. Advances in digital signal processing and control hardware have enabled real-time implementation across automotive, renewable energy and industrial automation applications. Remaining challenges include reliable low-speed performance, sensitivity to parameter uncertainty and the need for noise-resilient algorithms.
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Sensorless Control Techniques for Permanent Magnet Synchronous Motors publication trend
The graph below shows the total number of articles in sensorless control techniques for permanent magnet synchronous motors across all publications each year (not limited to Nature Index journals).
Technical terms
Back electromotive force (EMF): The voltage induced in the motor windings by rotor motion, used to infer rotor position and speed.
Sliding-mode observer (SMO): A nonlinear estimation technique that forces model error dynamics onto a sliding surface to robustly estimate states under parameter variation.
Model reference adaptive system (MRAS): A method that compares outputs of a reference model and an adaptive model to generate an error signal used for parameter estimation.
High-frequency signal injection: A technique that imposes a small alternating voltage onto the motor terminals to excite saliency effects and extract position information.
I-f method: A startup strategy that controls motor frequency and current to gradually initiate rotation before sensorless estimation becomes reliable.
References
- Sensorless Control of the Permanent Magnet Synchronous Motor. Sensors (2019).
- Sensorless Control Strategy of Permanent Magnet Synchronous Motor Based on Fuzzy Sliding Mode Observer. IEEE Access (2022).
- Switched PI Control Based MRAS for Sensorless Control of PMSM Drives Using Fuzzy-Logic-Controller. IEEE Open Journal of Power Electronics (2022).
- Research on Startup Process for Sensorless Control of PMSMs Based on I-F Method Combined With an Adaptive Compensator. IEEE Access (2020).
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