Optimal Duty Cycle Model Predictive Current Control of High-Altitude Ventilator Induction Motor With Extended Minimum Stator Current Operation

High-altitude ventilator has been utilized to blow the air into airship airbags to achieve flight control of the stratospheric airship. Owing to the thin air in the stratosphere, high-altitude ventilator induction motor operates at high-speed light-load condition. The traditional minimum stator current operation is employed to minimize conduction and switching losses below the rated speed. This paper extends this concept to the field-weakening region, and puts forward the extended minimum stator current operation (EMSCO) to obtain high efficiency at any speed. The EMSCO criterion is formalized as constrained optimization problem that is solved by breaking down into subproblems. The proposed EMSCO maps the torque reference onto the optimal field current and torque current references. In addition, optimal duty cycle model predictive current control (ODC-MPCC) is proposed to reduce the current ripple and computation burden compared with traditional MPCC. In ODC-MPCC, the novel cost function based on deadbeat voltage vector reduces the computation burden. The proposed ODC-MPCC of induction motor with EMSCO is verified effectively by simulation and experiment, which is compared with the traditional control strategy of induction motor.