Efficient I-F Startup Method for Refrigeration Compressors

This paper presents an efficient current-frequency (I-F) startup method for Permanent Magnet Synchronous Ma- chines (PMSMs) used in positive displacement refrigeration compressors, designed to enhance the startup efficiency and adaptability. Traditional I-F startup strategies often struggle under varying operational conditions due to their inability to dynamically adjust the q-axis current based on actual load torque. To address this limitation, a thermodynamic approach is employed to estimate the load torque using a compressor model and real-time operational conditions. This enables precise regulation of the reference current on the q-axis, significantly reducing power consumption and transition time to Field- Oriented Control (FOC). Both simulations and initial experimental results demonstrate substantial improvements over the conventional method, including a reduced convergence time and a lower energy consumption across different load scenarios. These findings suggest that the proposed I-F startup method can provide significant energy savings and improve operational efficiency in industrial refrigeration systems.