Method for determining a discharge pressure of a rolling piston compressor

A rolling piston compressor comprising:

• a casing defining a cylindrical cavity defining a central axis, a suction port, and a discharge port;
• an electric motor comprising a drive shaft, the drive shaft extending along the central axis;
• a rolling piston positioned within the cylindrical cavity, the rolling piston being eccentrically mounted on the drive shaft;
• a sliding vane that extends from the casing toward the rolling piston to maintain contact with the rolling piston as it rotates about the central axis, the sliding vane and the rolling piston dividing the cylindrical cavity into a suction volume in fluid communication with the suction port and a compression volume in fluid communication with the discharge port;
• and
• a controller operably coupled to the electric motor, the controller configured for:
• estimate a discharge pressure (Pd) within the compression volume based at least in part on a load torque (TL) and a load torque angle (θm), wherein estimating the discharge pressure (Pd) comprises empirically determining a relationship between the load torque (TL), the load torque angle (θm), and the discharge pressure (Pd);
• determine that the discharge pressure (Pd) is greater than a predetermined pressure limit (Pd-limit);
• and
• adjust at least one operating parameter of the rolling piston compressor to decrease the discharge pressure (Pd).

A method for operating a rolling piston compressor, the rolling piston compressor comprising a casing defining a cylindrical cavity defining a central axis, a suction port, and a discharge port, a rolling piston positioned within the cylindrical cavity, and a sliding vane that extends from the casing toward the rolling piston to maintain contact with the rolling piston as it rotates about a central axis, the sliding vane and the rolling piston dividing the cylindrical cavity into a suction volume in fluid communication with the suction port and a compression volume in fluid communication with the discharge port, the method comprising:

• estimating a discharge pressure (Pd) within the compression volume based at least in part on a load torque (TL) and a load torque angle (θm);
• determining that the discharge pressure (Pd) is greater than a predetermined pressure limit (Pd-limit);
• and
• adjusting at least one operating parameter of the rolling piston compressor to decrease the discharge pressure (Pd) by lowering a current limit or a torque limit for the rolling piston compressor.