Abstract: In view of the problems of speed sensor dependence and parameter drift in permanent magnet semi- direct drive pumping unit, a vector control method combining speed sensorless and parameter identification is proposed. A sliding mode observer is designed to replace speed sensors such as rotary transformers, and a model reference adaptive system model is constructed based on Popov hyperstability theory. The closed-loop system architecture of stator resistance, inductance and flux parameter identification is established synchronously. The experimental results show that the proposed method can accurately estimate the motor speed and dynamically track the parameter change through the model reference adaptive algorithm. Compared to the control scheme that relies on the rotating transformer, the new system eliminates the hardware cost of the sensor and significantly improves the system parameter estimation ability through the double closed-loop coordination of the sliding mode observer and parameter identification. The design provides a new solution for the stable operation of the oil pumping unit under harsh working conditions. 

Key words: speed sensorless, sliding mode observer, parameter identification, model reference adaptive method