Simulation study of a sensorless servo motor control algorithm based on the rotating high-frequency voltage injection method

Acquiring precise rotor position data is a fundamental prerequisite for maintaining the stable operation of permanent magnet synchronous motors (PMSMs) utilizing vector control schemes.Traditional methods rely on position sensors such as rotary transformers, which, whilst simple to implement and offering high precision, are susceptible to interference in extreme environments—including sub-zero temperatures, extreme heat, strong electromagnetic interference, or high-vibration conditions. This leads to increased detection errors, compromising both stability and responsiveness. Consequently, developing sensorless control techniques has become crucial for addressing complex application scenarios. The primary objective of this study is to implement a sensorless control architecture for salient-pole PMSMs. By injecting high-frequency voltage signals, the system derives the rotor's position without relying on mechanical sensors. In particular, the rotating high-frequency voltage injection (R-HFVI) technique is adopted. This involves superimposing balanced sinusoidal voltage signals onto the stationary    reference frame. By leveraging the magnetic saliency (inductance anisotropy) of the salient-pole motor, the rotor angle is successfully demodulated from the induced high-frequency currents. The system design incorporates signal processing stages, such as a delayed bandpass filter to eliminate fundamental noise, a synchronous shaft high-pass filter to isolate negative-sequence components, and a phase-locked loop combined with heterodyning to precisely estimate rotor angle and speed. Validations performed using the Matlab/Simulink platform covered a range of dynamic scenarios, such as steady-state operation at 300 r/min, ramping up from 100 r/min to 600 r/min, and slowing down to 500 r/min. The outcomes reveal that the speed estimation deviation is kept below 0.09 r/min, while the rotor angle error is strictly limited to 0.00005 rad. The system achieved rapid stabilization within 0.05 seconds, demonstrating the strategy's robustness and practicality in complex dynamic processes. This provides a viable pathway for high-performance servo drive systems.