Patent ID: 10291164

Abstract:
The present invention relates to a method of operating a variable speed motor (1) drivingly connected to a multiphase pump (3) via a shaft (4). A power transmission device (20) for transmission of power to the variable speed motor (1) from a power source (2) is provided. A first controller (30) is provided between the power source (2) and the power transmission device (20) for controlling the variable speed motor (1). A speed parameter (n) representative of a motor speed (nmot) is calculated in the first controller (30). A torque reference (Tref) is received in the first controller (30). A second controller (40) is provided in communication with the first controller (30) for compensation of the effect of the power transmission device (20). The second controller (40) comprises a representation of a compensation torque (ΔTmap) as a function of a mapped torque parameter (Tmap) and a mapped speed parameter (nmap). The second controller (40) is arranged to receive the torque reference (Tref) and the speed parameter (n) from the first controller (30). The compensation torque (ΔTmap) for the speed parameter (n) and torque reference (Tref) is calculated in the second controller (40) based on the said representation. Then, the first controller (30) is arranged to receive the compensation torque (ΔTmap) from the second controller (40) and the first controller is controlling the variable speed motor (1) based on the received compensation torque (ΔTmap), to keep the difference between the torque reference (Tref) and the shaft torque (Tmot) as small as possible.