This paper establishes a non-linear model for synchronous reluctance motors (SynRM) considering self-saturation and cross-saturation effects. A sensorless control method based on the combination of active flux method and high-frequency (HF) voltage injection is proposed. The proposed observer exhibits a broad operating speed range, seamlessly transitioning between the two models according to the reference speed. A synchronous reluctance motor experimental platform is built to validate the proposed control strategy. The experimental results are analyzed, and the findings indicate that the proposed control method based on the combination of active flux method and high-frequency voltage injection achieves stable operation of synchronous reluctance motors under all operating conditions and exhibits good robustness.