Abstract: The variable frequency refrigerator compressor has a periodic pulse load characteristic. Under heavy load conditions such as high system pressure or large pressure difference, the traditional sensorless three-stage starting method has problems such as insufficient starting ability, large starting jitter, and poor starting stability. In response to the above issues, this article conducts theoretical research on three key processes: A rotation delay positioning method was proposed in the rotor pre-positioning stage, effectively avoiding blind spots in positioning and ensuring smooth and accurate positioning. In the I-F open-loop drag section, the effects of key parameters such as open-loop drag current, reference acceleration, target speed, low voltage, and overload inductance saturation on startup were compared and analyzed. Finally, smooth state switching is achieved through the linear fitting algorithm of rotor angle. On the basis of theoretical analysis, a variable frequency compressor was installed for experimental verification, and the results showed that compared to the traditional three-stage starting method, the optimized algorithm has strong starting ability, rapid and stable starting process, and high reliability, which proves the effectiveness and advantages of the optimization algorithm.

Key words: Refrigerator compressor, Sensorless three-stage starting method, Rotation delay positioning method, I-F open-loop drag, State switching